MathDB
Problems
Contests
National and Regional Contests
USA Contests
USA - Middle School Tournaments
Math Invitational for Girls
2018 MIG
2018 MIG
Part of
Math Invitational for Girls
Subcontests
(25)
25
1
Hide problems
2018 Individual #25
The figure below contains two squares which share an edge, one with side length
200
200
200
units and the other with side length
289
289
289
units. The figure is divided into a whole number of regions, each with an equal whole number area but not necessarily of the same shape. Given that there is more than one region and each region has an area greater than
1
1
1
, find the sum of the number of regions and the area of each region. [asy] size(4cm); draw((0,0)--(200,0)--(200,200)--(0,200)--cycle); label("
200
200
200
",(0,0)--(200,0)); label("
289
289
289
",(200,0)--(489,0)); draw((200,0)--(489,0)--(489,289)--(200,289)--cycle); [/asy]
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
704
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
874
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
924
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
978
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
1028
<span class='latex-bold'>(A) </span> 704\qquad<span class='latex-bold'>(B) </span> 874\qquad<span class='latex-bold'>(C) </span> 924\qquad<span class='latex-bold'>(D) </span> 978\qquad<span class='latex-bold'>(E) </span> 1028
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
704
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
874
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
924
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
978
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
1028
24
1
Hide problems
2018 Individual #24
The sides of
△
A
B
C
\triangle ABC
△
A
BC
form an arithmetic sequence of integers. Incircle
I
I
I
is tangent to
A
B
AB
A
B
,
B
C
BC
BC
, and
C
A
CA
C
A
at
D
D
D
,
E
E
E
, and
F
F
F
, respectively. Given that
D
B
=
3
2
DB = \tfrac32
D
B
=
2
3
,
F
A
=
1
2
FA = \tfrac12
F
A
=
2
1
, find the radius of
I
I
I
.
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
1
2
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
15
7
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
15
6
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
2
15
9
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
15
4
<span class='latex-bold'>(A) </span> \dfrac12\qquad<span class='latex-bold'>(B) </span> \dfrac{\sqrt{15}}7\qquad<span class='latex-bold'>(C) </span> \dfrac{\sqrt{15}}6\qquad<span class='latex-bold'>(D) </span> \dfrac{2\sqrt{15}}{9}\qquad<span class='latex-bold'>(E) </span> \dfrac{\sqrt{15}}{4}
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
2
1
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
7
15
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
6
15
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
9
2
15
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
4
15
23
1
Hide problems
2018 Individual #23
Diagonal
A
C
AC
A
C
is drawn in rectangle
A
B
C
D
ABCD
A
BC
D
. Points
E
E
E
and
F
F
F
are placed on
B
C
BC
BC
such that
C
E
:
E
F
:
F
B
=
2
:
1
:
1
CE:EF:FB=2:1:1
CE
:
EF
:
FB
=
2
:
1
:
1
. Let
G
G
G
be the intersection of
D
F
DF
D
F
with
A
C
AC
A
C
and
H
H
H
the intersection of
D
E
DE
D
E
with
A
C
AC
A
C
. Given that
A
D
=
4
AD=4
A
D
=
4
and
A
B
=
8
AB=8
A
B
=
8
, find the length of
G
H
GH
G
H
. Express your answer as a common fraction in simplest radical form.https://cdn.artofproblemsolving.com/attachments/4/c/b69d79cd47bcb945e7a489533eb9761ccc7ccd.png
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
4
5
21
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
8
5
21
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
10
5
21
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
4
5
5
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
5
<span class='latex-bold'>(A) </span> \dfrac{4\sqrt5}{21}\qquad<span class='latex-bold'>(B) </span> \dfrac{8\sqrt5}{21}\qquad<span class='latex-bold'>(C) </span> \dfrac{10\sqrt5}{21}\qquad<span class='latex-bold'>(D) </span> \dfrac{4\sqrt5}{5}\qquad<span class='latex-bold'>(E) </span> \sqrt5
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
21
4
5
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
21
8
5
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
21
10
5
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
5
4
5
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
5
22
1
Hide problems
2018 Individual #22
Country
A
A
A
uses a currency known as the shell. The nation uses only two coins, each worth a whole number of shells. The largest amount of shell not obtainable using a combination of these two coins is
215
215
215
. Find the number of possible pairs of values these two coins could have. (a value of
15
15
15
and
4
4
4
is the same as having a
4
4
4
and
15
15
15
)
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
6
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
7
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
8
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
9
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
10
<span class='latex-bold'>(A) </span> 6\qquad<span class='latex-bold'>(B) </span> 7\qquad<span class='latex-bold'>(C) </span> 8\qquad<span class='latex-bold'>(D) </span> 9\qquad<span class='latex-bold'>(E) </span> 10
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
6
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
7
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
8
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
9
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
10
21
1
Hide problems
2018 Individual #21
Find the sum:
11
×
(
2
0
)
+
10
×
(
3
1
)
+
9
×
(
4
2
)
+
⋯
+
2
×
(
11
9
)
+
(
12
10
)
11 \times \dbinom20 + 10 \times \dbinom31 + 9 \times \dbinom42 + \cdots + 2 \times \dbinom{11}9 + \dbinom{12}{10}
11
×
(
0
2
)
+
10
×
(
1
3
)
+
9
×
(
2
4
)
+
⋯
+
2
×
(
9
11
)
+
(
10
12
)
Where
(
n
r
)
\tbinom{n}{r}
(
r
n
)
is combination function given by
n
!
r
!
(
n
−
r
)
!
\tfrac{n!}{r!(n-r)!}
r
!
(
n
−
r
)!
n
!
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
351
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
841
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
901
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
991
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
1001
<span class='latex-bold'>(A) </span> 351\qquad<span class='latex-bold'>(B) </span> 841\qquad<span class='latex-bold'>(C) </span> 901\qquad<span class='latex-bold'>(D) </span> 991\qquad<span class='latex-bold'>(E) </span> 1001
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
351
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
841
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
901
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
991
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
1001
20
1
Hide problems
2018 Individual #20
Point
O
O
O
is selected in equilateral
△
A
B
C
\triangle ABC
△
A
BC
such that the sum of the distances from
O
O
O
to each side of
A
B
C
ABC
A
BC
is
15
15
15
. Compute the area of
A
B
C
ABC
A
BC
.https://cdn.artofproblemsolving.com/attachments/4/0/dd573985a7c98f23fd05d11e95c4b908eaa895.png
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
15
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
30
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
50
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
75
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
225
3
<span class='latex-bold'>(A) </span> 15\sqrt3\qquad<span class='latex-bold'>(B) </span> 30\sqrt3\qquad<span class='latex-bold'>(C) </span> 50\sqrt3\qquad<span class='latex-bold'>(D) </span> 75\sqrt3\qquad<span class='latex-bold'>(E) </span> 225\sqrt3
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
15
3
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
30
3
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
50
3
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
75
3
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
225
3
19
1
Hide problems
2018 Individual #19
Rectangle
A
B
C
D
ABCD
A
BC
D
, with integer side lengths, has equal area and perimeter. What is the positive difference between the two possible areas of
A
B
C
D
ABCD
A
BC
D
?
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
0
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
2
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
4
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
5
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
6
<span class='latex-bold'>(A) </span> 0\qquad<span class='latex-bold'>(B) </span> 2\qquad<span class='latex-bold'>(C) </span> 4\qquad<span class='latex-bold'>(D) </span> 5\qquad<span class='latex-bold'>(E) </span> 6
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
0
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
2
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
4
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
5
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
6
18
1
Hide problems
2018 Individual #18
How many paths are there from
A
A
A
to
B
B
B
in the following diagram if only moves downward are allowed?https://cdn.artofproblemsolving.com/attachments/f/d/62a14f7959cc0461543b0f76bba51be9786847.png
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
65
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
67
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
70
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
74
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
75
<span class='latex-bold'>(A) </span> 65\qquad<span class='latex-bold'>(B) </span> 67\qquad<span class='latex-bold'>(C) </span> 70\qquad<span class='latex-bold'>(D) </span> 74\qquad<span class='latex-bold'>(E) </span> 75
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
65
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
67
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
70
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
74
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
75
17
1
Hide problems
2018 Individual #17
Two standard six sided dice labeled with the numbers
1
1
1
-
6
6
6
are rolled, and the numbers that come up are multiplied. What is the probability that their product is a multiple of five?
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
1
4
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
5
18
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
11
36
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
1
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
4
9
<span class='latex-bold'>(A) </span> \dfrac14\qquad<span class='latex-bold'>(B) </span> \dfrac5{18}\qquad<span class='latex-bold'>(C) </span> \dfrac{11}{36}\qquad<span class='latex-bold'>(D) </span> \dfrac13\qquad<span class='latex-bold'>(E) </span> \dfrac49
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
4
1
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
18
5
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
36
11
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
3
1
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
9
4
16
1
Hide problems
2018 Individual #16
A triangle with area
60
units
2
60\text{ units}^2
60
units
2
has vertices with coordinates of
(
−
15
,
x
)
(-15,x)
(
−
15
,
x
)
,
(
0
,
x
)
(0,x)
(
0
,
x
)
, and
(
25
,
0
)
(25,0)
(
25
,
0
)
. Find the largest possible value of
x
x
x
.
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
−
8
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
−
4
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
4
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
8
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
16
<span class='latex-bold'>(A) </span> {-}8\qquad<span class='latex-bold'>(B) </span> {-}4\qquad<span class='latex-bold'>(C) </span> 4\qquad<span class='latex-bold'>(D) </span> 8\qquad<span class='latex-bold'>(E) </span> 16
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
−
8
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
−
4
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
4
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
8
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
16
15
1
Hide problems
2018 Individual #15
Gordon has the least number of coins (half-dollars, quarters, dimes, nickels, pennies) needed to make 99\cent. He randomly chooses one. What is the probability that it is a penny?
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
1
5
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
1
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
1
2
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
2
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
3
4
<span class='latex-bold'>(A) </span> \dfrac15\qquad<span class='latex-bold'>(B) </span> \dfrac13\qquad<span class='latex-bold'>(C) </span> \dfrac12\qquad<span class='latex-bold'>(D) </span> \dfrac23\qquad<span class='latex-bold'>(E) </span> \dfrac34
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
5
1
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
3
1
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
2
1
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
3
2
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
4
3
14
1
Hide problems
2018 Individual #14
How many integers between
80
80
80
and
100
100
100
are prime?
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
4
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
5
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
6
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
7
<span class='latex-bold'>(A) </span> 3\qquad<span class='latex-bold'>(B) </span> 4\qquad<span class='latex-bold'>(C) </span> 5\qquad<span class='latex-bold'>(D) </span> 6\qquad<span class='latex-bold'>(E) </span> 7
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
3
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
4
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
5
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
6
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
7
13
1
Hide problems
2018 Individual #13
Find the sum of the
2
2
2
smallest prime factors of
2
1024
−
1
2^{1024} - 1
2
1024
−
1
.
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
4
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
6
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
8
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
10
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
12
<span class='latex-bold'>(A) </span> 4\qquad<span class='latex-bold'>(B) </span> 6\qquad<span class='latex-bold'>(C) </span> 8\qquad<span class='latex-bold'>(D) </span> 10\qquad<span class='latex-bold'>(E) </span> 12
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
4
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
6
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
8
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
10
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
12
12
1
Hide problems
2018 Individual #12
A unit cube is sliced by a plane passing through two of its vertices and the midpoints of the edges it passes through. What is the area of the rhombus formed by this intersection?https://cdn.artofproblemsolving.com/attachments/3/5/3ed19fa0b4d454a3afc16c6bcf9d69403f6b2c.png
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
6
2
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
2
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
6
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
2
6
<span class='latex-bold'>(A) </span> \dfrac{\sqrt6}{2}\qquad<span class='latex-bold'>(B) </span>\sqrt2\qquad<span class='latex-bold'>(C) </span>\sqrt3\qquad<span class='latex-bold'>(D) </span>\sqrt6\qquad<span class='latex-bold'>(E) </span>2\sqrt6
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
2
6
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
2
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
3
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
6
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
2
6
11
1
Hide problems
2018 Individual #11
Square
A
B
C
D
ABCD
A
BC
D
and triangle
A
B
E
ABE
A
BE
have equal area. Square
A
B
C
D
ABCD
A
BC
D
has sidelength
4
4
4
, while triangle
A
B
E
ABE
A
BE
has height
h
h
h
and base
4
4
4
. Find the value of
h
h
h
. https://cdn.artofproblemsolving.com/attachments/7/c/efe7bed4232f9d2440f5719d6f2ddae0ef7d05.png
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
4
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
2
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
4
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
6
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
8
<span class='latex-bold'>(A) </span>\dfrac43\qquad<span class='latex-bold'>(B) </span>2\qquad<span class='latex-bold'>(C) </span>4\qquad<span class='latex-bold'>(D) </span>6\qquad<span class='latex-bold'>(E) </span>8
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
3
4
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
2
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
4
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
6
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
8
10
2
Hide problems
2018 Individual #10
A survey was taken in Ms. Susan's class to see what grades the class received: [img width=35]https://cdn.artofproblemsolving.com/attachments/5/c/e96cb42de6d5e1b100f37bbb71768d399842cb.png What percent of the class received an "A"?
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
3
%
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
5
%
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
10
%
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
15
%
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
27
%
<span class='latex-bold'>(A) </span>3\%\qquad<span class='latex-bold'>(B) </span>5\%\qquad<span class='latex-bold'>(C) </span>10\%\qquad<span class='latex-bold'>(D) </span>15\%\qquad<span class='latex-bold'>(E) </span>27\%
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
3%
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
5%
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
10%
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
15%
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
27%
2018 Team #10
Let
P
(
x
)
=
x
2
+
a
x
+
b
P(x) = x^2 + ax + b
P
(
x
)
=
x
2
+
a
x
+
b
. The two zeros of
P
P
P
,
r
1
r_1
r
1
and
r
2
r_2
r
2
, satisfy the equation
∣
r
1
2
−
r
2
2
∣
=
17
|r_1^2 -r_2^2| = 17
∣
r
1
2
−
r
2
2
∣
=
17
. Give that
a
,
b
>
1
a, b > 1
a
,
b
>
1
and are both integers, find
P
(
1
)
P(1)
P
(
1
)
.
9
2
Hide problems
2018 Individual #9
Define
f
(
x
)
=
x
2
+
5
f(x) = x^2 + 5
f
(
x
)
=
x
2
+
5
. Find the product of all
x
x
x
such that
f
(
x
)
=
14
f(x) = 14
f
(
x
)
=
14
.
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
−
9
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
−
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
0
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
9
<span class='latex-bold'>(A) </span>{-}9\qquad<span class='latex-bold'>(B) </span>{-}3\qquad<span class='latex-bold'>(C) </span>0\qquad<span class='latex-bold'>(D) </span>3\qquad<span class='latex-bold'>(E) </span>9
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
−
9
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
−
3
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
0
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
3
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
9
2018 Team #9
A certain
4
4
4
digit prime number has all prime digits. When any one of the digits is removed, the remaning three digits form a composite number in their initial order (i.e. if
1234
1234
1234
were the answer, then
123
123
123
,
234
234
234
,
134
134
134
, and
124
124
124
would have to be composite.) What is the largest possible value of this number?
8
2
Hide problems
2018 Individual #8
The set of natural numbers are arranged as so:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
⋮
\begin{array}{ccccccccc} & & & & 1 & & & &\\ & & & 2 & 3 & 4 & & &\\ & & 5 & 6 & 7 & 8 & 9 &\\ & 10 & 11 & 12 & 13 & 14 & 15 & 16 &\\ 17 & 18 & 19 & 20 & 21 & 22 & 23 & 24 & 25\\ & & & & \vdots & & & & \end{array}
17
10
18
5
11
19
2
6
12
20
1
3
7
13
21
⋮
4
8
14
22
9
15
23
16
24
25
so that each row has
2
2
2
more numbers in it, and the rows are centered. What is the number under
49
49
49
?
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
60
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
61
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
62
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
63
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
64
<span class='latex-bold'>(A) </span>60\qquad<span class='latex-bold'>(B) </span>61\qquad<span class='latex-bold'>(C) </span>62\qquad<span class='latex-bold'>(D) </span>63\qquad<span class='latex-bold'>(E) </span>64
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
60
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
61
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
62
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
63
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
64
2018 Team #8
A marathon runner has a very peculiar way of training for a marathon. On the first day of week
1
1
1
, the runner runs a distance equivalent to the first prime number. On the second day, the runner runs a distance equal to the second prime number, continuing this pattern until the
7
7
7
th day of the week. Each successive week, the runner runs one more mile per day than they did on the same day of the previous week. The runner continues this process until the average distance run each week exceeds the distance of a marathon (
26.2
26.2
26.2
miles). How many weeks does the marathoner train?
7
2
Hide problems
2018 Individual #7
How many perfect squares are greater than
0
0
0
but less than or equal to
100
100
100
?
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
6
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
7
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
8
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
9
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
10
<span class='latex-bold'>(A) </span>6\qquad<span class='latex-bold'>(B) </span>7\qquad<span class='latex-bold'>(C) </span>8\qquad<span class='latex-bold'>(D) </span>9\qquad<span class='latex-bold'>(E) </span>10
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
6
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
7
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
8
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
9
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
10
2018 Team #7
The accuracy of a mystic's prediction is related to the volume of his or her crystal ball by the equation
P
=
1
−
(
0.999
)
V
P = 1 - (0.999)^V
P
=
1
−
(
0.999
)
V
, where
P
P
P
is the probability the mystic's prediction is correct and
V
V
V
is the volume of his ball in cubic centimeters. These crystal balls are sold wth radii that are a whole number of centimeters. What is the radius (in centimeters) of the smallest ball that gives the mystic over a
99
%
99\%
99%
chance to make an accurate prediction.
6
2
Hide problems
2018 Individual #6
How many more hours are in
10
10
10
years than seconds in
1
1
1
day?
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
1000
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
1100
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
1150
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
1200
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
1300
<span class='latex-bold'>(A) </span>1000\qquad<span class='latex-bold'>(B) </span>1100\qquad<span class='latex-bold'>(C) </span>1150\qquad<span class='latex-bold'>(D) </span>1200\qquad<span class='latex-bold'>(E) </span>1300
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
1000
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
1100
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
1150
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
1200
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
1300
2018 Team #6
Circles
A
\text{A}
A
and
B
\text{B}
B
are concentric, with the radius of
A
\text{A}
A
being
17
\sqrt{17}
17
times the radius of
B
B
B
. The largest line segment that can be draw in the region bounded by the two circles has length
32
32
32
. Compute the radius of circle
B
B
B
.https://cdn.artofproblemsolving.com/attachments/7/4/6bc4aed9842cdfbeb95853d508a22b61a10c9c.png
5
2
Hide problems
2018 Individual #5
Some of the values produced by two functions,
f
(
x
)
f(x)
f
(
x
)
and
g
(
x
)
g(x)
g
(
x
)
, are shown below. Find
f
(
g
(
3
)
)
f(g(3))
f
(
g
(
3
))
\begin{tabular}{c||c|c|c|c|c}
x
x
x
& 1 & 3 & 5 & 7 & 9 \\ \hline\hline
f
(
x
)
f(x)
f
(
x
)
& 3 & 7 & 9 & 13 & 17 \\ \hline
g
(
x
)
g(x)
g
(
x
)
& 54 & 9 & 25 & 19 & 44 \end{tabular}
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
7
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
8
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
13
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
17
<span class='latex-bold'>(A) </span>3\qquad<span class='latex-bold'>(B) </span>7\qquad<span class='latex-bold'>(C) </span>8\qquad<span class='latex-bold'>(D) </span>13\qquad<span class='latex-bold'>(E) </span>17
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
3
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
7
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
8
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
13
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
17
2018 Team #5
A fair six sided die is rolled to give a number
n
n
n
. A fair two sided coin is then flipped
n
2
n^2
n
2
times. Find the expected number of heads flipped. Express your answer as a common fraction.
4
2
Hide problems
2018 Individual #4
What is the positive difference between the sum of the first
5
5
5
positive even integers and the first
5
5
5
positive odd integers?
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
2
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
4
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
5
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
6
<span class='latex-bold'>(A) </span>2\qquad<span class='latex-bold'>(B) </span>3\qquad<span class='latex-bold'>(C) </span>4\qquad<span class='latex-bold'>(D) </span>5\qquad<span class='latex-bold'>(E) </span>6
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
2
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
3
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
4
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
5
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
6
2018 Team #4
In regular hexagon
A
B
C
D
E
F
ABCDEF
A
BC
D
EF
, lines
A
C
AC
A
C
and
B
E
BE
BE
are drawn, and their intersection is labeled
G
G
G
. What fraction of the area of
A
B
C
D
E
F
ABCDEF
A
BC
D
EF
is contained in triangle
A
B
G
ABG
A
BG
? https://cdn.artofproblemsolving.com/attachments/1/a/47d6226b18cb2b7c941287b1628b56423909b8.png
3
2
Hide problems
2018 Individual #3
Solve for
x
x
x
if
4
x
+
1
=
37
4x + 1 = 37
4
x
+
1
=
37
.
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
4
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
5
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
7
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
9
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
10
<span class='latex-bold'>(A) </span>4\qquad<span class='latex-bold'>(B) </span>5\qquad<span class='latex-bold'>(C) </span>7\qquad<span class='latex-bold'>(D) </span>9\qquad<span class='latex-bold'>(E) </span>10
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
4
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
5
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
7
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
9
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
10
2018 Team #3
6
6
6
cats can eat
6
6
6
fish in
1
1
1
day, and
c
c
c
cats can eat
91
91
91
fish in
d
d
d
days. Given that
c
c
c
and
d
d
d
are both whole numbers, and the number of cats,
c
c
c
, is more than
1
1
1
but less than
10
10
10
, find
c
+
d
c + d
c
+
d
.
2
2
Hide problems
2018 Individual #2
Edward is trying to spell the word "CAT". He has an equal chance of spelling the word in any order of letters (i.e. TAC or TCA). What is the probability that he spells "CAT" incorrectly?
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
1
6
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
1
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
1
2
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
2
3
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
5
6
<span class='latex-bold'>(A) </span>\dfrac16\qquad<span class='latex-bold'>(B) </span>\dfrac13\qquad<span class='latex-bold'>(C) </span>\dfrac12\qquad<span class='latex-bold'>(D) </span>\dfrac23\qquad<span class='latex-bold'>(E) </span>\dfrac56
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
6
1
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
3
1
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
2
1
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
3
2
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
6
5
2018 Team #2
The MIG is planning a lottery to give out prizes after the written tests, and the plan is very special. Contestants will be divided into prize groups in order to potentially receive a prize. However, based on the number of contestants, the ideal number of groups don't work. For example, when dividing into
4
4
4
groups, there are
3
3
3
left over. When dividing into
5
5
5
groups, there's
2
2
2
left over. When dividing into
6
6
6
groups, theres
1
1
1
left over. Finally, when dividing into
7
7
7
groups, there are
2
2
2
left over. With the knowledge that there are less than
300
300
300
participants in the MIG, how many participants are there?
1
2
Hide problems
2018 Individual #1
Evaluate
1
+
2
+
4
+
7
1 + 2 + 4 + 7
1
+
2
+
4
+
7
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
14
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
15
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
16
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
17
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
18
<span class='latex-bold'>(A) </span>14\qquad<span class='latex-bold'>(B) </span>15\qquad<span class='latex-bold'>(C) </span>16\qquad<span class='latex-bold'>(D) </span>17\qquad<span class='latex-bold'>(E) </span>18
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
14
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
15
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
16
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
17
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
18
2018 Team #1
For how many numbers
n
n
n
ranging from
1
1
1
to
10
10
10
, inclusive, is
5
n
+
1
5n + 1
5
n
+
1
a prime number?