The ratio of male to female students in a college for five years is plotted in the following line graph. The graph shows the male-to-female ratio for years 2007 through 2011. In 2007 the ratio is 2.5, and in 2008 the ratio is 3.0. If the number of female students doubled in 2008, by what percent did the number of male students increase in 2008?

GATE 2014 · General Aptitude · Line Graph · medium

Answer: The number of male students increased by 140% in 2008.

1. Set up male counts using ratio and female data: Let female count in 2007 = F. Male count in 2007 = R_2007 x F = 2.5F. Female count in 2008 = 2F (given doubled). Male count in 2008 = R_2008 x 2F = 3.0 x 2F = 6F.
2. Compute percentage increase in male students: % increase = (6F - 2.5F) / (2.5F) x 100 = 3.5F / 2.5F x 100 = (3.5/2.5) x 100 = 1.4 x 100 = 140%.