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# A class in a certain school consists of boys and girls in the ratio of

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Joined: 25 Dec 2018
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Concentration: General Management, Finance
GMAT Date: 02-18-2019
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A class in a certain school consists of boys and girls in the ratio of  [#permalink]

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13 Jun 2019, 00:34
00:00

Difficulty:

55% (hard)

Question Stats:

53% (02:13) correct 47% (01:52) wrong based on 30 sessions

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A class in a certain school consists of boys and girls in the ratio of 2:1. In a mathematics test, 60% of the class passed the test. If 40% of the boys failed the test, what percentage of the class are girls who passed the test?

A. 10%
B. 20%
C. 30%
D. 40%
E. 60%
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Re: A class in a certain school consists of boys and girls in the ratio of  [#permalink]

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13 Jun 2019, 06:08
Assume 30 students in class. So boys 20 and girls 10.

60%passed so 18 students passed.
40% of boys failed. So 60% of boys = .6*20=12 passed the test.
Remaining 6 students who passed must be girls; so % is 6/30*100=20% IMO B.

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Re: A class in a certain school consists of boys and girls in the ratio of  [#permalink]

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13 Jun 2019, 07:47
mangamma wrote:
A class in a certain school consists of boys and girls in the ratio of 2:1. In a mathematics test, 60% of the class passed the test. If 40% of the boys failed the test, what percentage of the class are girls who passed the test?

A. 10%
B. 20%
C. 30%
D. 40%
E. 60%

The easiest way to solving this problem is by assuming a random number for the total
number of students in the class. Arvind42 has already demonstrated this.

If there are 3x students in the class and 40% of the boys failed the test, 60% or 0.6*2x = 1.2x pass.

We are told that 60% of the class passes the test -> 0.6*3x or 1.8x of the class passes the test. The
remaining 0.6x(1.8x - 1.2x) are girls who pass the test.

Therefore, the percentage of girls in the class who pass the test are $$\frac{0.6x}{3x}$$ = 20%(Option B)
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Re: A class in a certain school consists of boys and girls in the ratio of   [#permalink] 13 Jun 2019, 07:47
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