Find the number of nondecreasing 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.
=>
(x38x1)+(x38x2)+....+(x38x37) =
(x75x38)+(x74x38)+...+(x39x38)
if x38 is the mean and median

Posted by Praneeth
on 20100806 19:08:15 