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2021 MMATHS
6
6
Part of
2021 MMATHS
Problems
(1)
MMATHS 2021, Problem 6: It's A Coinflip
Source:
10/31/2021
Ben flips a coin 10 times and then records the absolute difference between the total number of heads and tails he's flipped. He then flips the coin one more time and records the absolute difference between the total number of heads and tails he's flipped. If the probability that the second number he records is greater than the first can be expressed as
a
b
\frac{a}{b}
b
a
for positive integers
a
,
b
a,b
a
,
b
with
gcd
(
a
,
b
)
=
1
\gcd (a,b) = 1
g
cd
(
a
,
b
)
=
1
, then find
a
+
b
a + b
a
+
b
.Proposed by Vismay Sharan
Yale
MMATHS