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Brazil Undergrad MO
2018 Brazil Undergrad MO
14
14
Part of
2018 Brazil Undergrad MO
Problems
(1)
Arithmetic mean of all values
Source: Brazil Undergrad MO - Galois-Noether 2018 #14
11/26/2019
What is the arithmetic mean of all values of the expression
∣
a
1
−
a
2
∣
+
∣
a
3
−
a
4
∣
| a_1-a_2 | + | a_3-a_4 |
∣
a
1
−
a
2
∣
+
∣
a
3
−
a
4
∣
Where
a
1
,
a
2
,
a
3
,
a
4
a_1, a_2, a_3, a_4
a
1
,
a
2
,
a
3
,
a
4
is a permutation of the elements of the set {
1
,
2
,
3
,
4
1,2,3,4
1
,
2
,
3
,
4
}?
modulo
algebra
Brazilian Math Olympiad
college contests