1984 AIME Problems/Problem 4
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Problem
Let 
be a list of positive integers - not necessarily distinct - in which the number 
appears. The arithmetic mean of the numbers in is 
. However, if is removed, the arithmetic mean of the numbers is 
. What's the largest number that can appear in ?
Solution
Suppose has 
members other than 68, and the sum of these members is 
. Then we're given that 
and 
. Multiplying to clear denominators, we have 
and 
so 
, 
and 
. Because the sum and number of the elements of are fixed, if we want to maximize the largest number in , we should take all but one member of to be as small as possible. Since all members of are positive integers, the smallest possible value of a member is 1. Thus the largest possible element is 
.
See also
| 1984 AIME (Problems • Resources) | ||
| Preceded by Problem 3 | Followed by Problem 5 | |
| 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 | ||
