GATE | GATE-CS-2014-(Set-2) | Question 65

The ratio of male to female students in a college for five years is plotted in the following line graph. If the number of female students doubled in 2009, by what percent did the number of male students increase in 2009?
GATECS2014Q92
(A) 120
(B) 140
(C) 160
(D) 180


Answer: (B)

Explanation:

Let x represent the males and y represent the females.

In 2008.
x / y = 2.5 -----------(1)

In 2009.
M / 2y = 3-------------(2)

where M is the total number of males in 2009.

Now x = 2.5y (from (1))
and M = 6y ( from (2))

hence increased number of males in 2009 are 
M - x = 6y - 2.5y = 3.5y

Now the increase in % of males =

(change in no of males / initial number)*100

= (3.5y / x )*100 = (3.5 / 2.5)*100 = 140 
                                 (given x/y = 2.5)

Hence, B is the right option.


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