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# In a certain class, 3/10 of the boys and 4/10 of the girls walk

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General GMAT Forum Moderator
Joined: 29 Jan 2015
Posts: 1091
Location: India
WE: General Management (Non-Profit and Government)
In a certain class, 3/10 of the boys and 4/10 of the girls walk  [#permalink]

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08 Jan 2019, 05:48
2
00:00

Difficulty:

45% (medium)

Question Stats:

77% (02:11) correct 23% (02:08) wrong based on 13 sessions

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In a certain class, 3/10 of the boys and 4/10 of the girls walk to school. If 9/25 of the students walk to school, what fraction of the students are girls and walk to school?

A. 1/5

B. 4/15

C. 6/25

D. 8/25

E. 3/2

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Manager
Joined: 09 Mar 2018
Posts: 196
Location: India
Re: In a certain class, 3/10 of the boys and 4/10 of the girls walk  [#permalink]

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08 Jan 2019, 07:00
rohan2345 wrote:
In a certain class, 3/10 of the boys and 4/10 of the girls walk to school. If 9/25 of the students walk to school, what fraction of the students are girls and walk to school?

A. 1/5

B. 4/15

C. 6/25

D. 8/25

E. 3/2

Good question, Here is my approach

Let Boys be x and Girls be y, WTS - Walk to school

Total students x+y

----------------B---------------G----------------Total
WTS--------(3/10)*x-------(4/10) * y-------(9/25) * (x+y)
----------------x----------------y---------------x + y

To find $$\frac{G(WTS)}{Total(WTS)}$$
$$\frac{3}{10}$$*x + $$\frac{4}{10}$$ * y = $$\frac{9}{25}$$ * (x+y)
Solving above will give
3x=2y
$$\frac{x}{y}$$ = $$\frac{2}{3}$$

x = $$\frac{2y}{3}$$

$$\frac{G(WTS)}{Total(WTS)}$$

=> $$\frac{4y}{10}$$ * $$\frac{3}{5y}$$
=> $$\frac{6}{25}$$

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Intern
Joined: 24 Oct 2017
Posts: 5
GMAT 1: 620 Q49 V25
In a certain class, 3/10 of the boys and 4/10 of the girls walk  [#permalink]

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08 Jan 2019, 09:37
Let the total number of Girls be G and Boys be B

Total number of students = B + G

Fraction of Girls walking to school = 4G/10 ----- (i)
Fraction of Boys walking to school = 3B/10 ----- (ii)

Fraction of students walking to school = 9(Total)/25 = 9(B+G)/25 ----- (iii)

eq(i) + eq(ii) = eq(iii)

=> 4G/10 + 3B/10 = (9B + 9G)/25
Solving, we get
B = $$\frac{2G}{3}$$ -----(iv)

Now, the ratio of girls walking to school to the total number of students
$$\frac{(4G|10)}{(B+G)}$$

from (iv)
=> $$\frac{(4G|10)}{(2G|3 + G)}$$
=> $$\frac{12}{50}$$
=> $$\frac{6}{25}$$

In a certain class, 3/10 of the boys and 4/10 of the girls walk &nbs [#permalink] 08 Jan 2019, 09:37
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