门| GATE-CS-2014-(Set-2) |第 65 题

下面的折线图绘制了五年来一所大学的男女生比例。如果 2009 年女学生人数翻了一番，那么 2009 年男学生人数增加了百分之多少?

(一) 120
(乙) 140
(三) 160
(四) 180答案：(乙)
解释：

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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