Symbiosis National Aptitude Test SNAP 2013 Paper

The maximum sum would occur when we take the sum of all the positive terms of the series.
The series 25, 24.5, 24, 23.5, 23, ....... 1, 0.5, 0 has 51 terms. The sum of the series would be given by:
n × average = 51 × 12.5 = 637.5