Find the number of non-decreasing sequences of 75 integers from 1 to 75 which have same mean as the median.
if x is the average of some numbers, then sum of
differences of every number less than x and x is equal
to sum of differences of every number greater than x
and x.
=>
(x38-x1)+(x38-x2)+....+(x38-x37) =
(x75-x38)+(x74-x38)+...+(x39-x38)
if x38 is the mean and median
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Posted by Praneeth
on 2010-08-06 19:08:15 |
hint
