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Joined: 16 May 2014
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GRE 1: Q165 V161
GRE Math Challenge #24-Yesterday, a certain school had
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Updated on: 17 Feb 2020, 04:26
Updated on: 17 Feb 2020, 04:26
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Yesterday, a certain school had an equal number of boys and girls. Today, 18 boys left the school, and the ratio of the number of boys to girls is now 3 to 4.
A)The quantity in Column A is greater.
B)The quantity in Column B is greater.
C)The two quantities are equal.
D)The relationship cannot be determined from the information given.
Quantity A |
Quantity B |
Number of boys in the school now |
72 |
A)The quantity in Column A is greater.
B)The quantity in Column B is greater.
C)The two quantities are equal.
D)The relationship cannot be determined from the information given.
Originally posted by soumya1989 on 15 Sep 2014, 13:51.
Last edited by Carcass on 17 Feb 2020, 04:26, edited 1 time in total.
Last edited by Carcass on 17 Feb 2020, 04:26, edited 1 time in total.
Updated
Re: GRE Math Challenge #24
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15 Sep 2014, 22:41
15 Sep 2014, 22:41
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Yesterday, we have no. of boys (b) = no. of girls (g)=> b=g ----(i)
Today, (b-18) : g = 3:4 => (b-18)/g = 3/4 => 4(b-18) = 3g ----- (ii)
From, equations, (i) & (ii) => 4b - 72 = 3b => b=72 => Yesterday, the number of boys were 72 and today their number has reduced to (72-18) to 54.
Today, (b-18) : g = 3:4 => (b-18)/g = 3/4 => 4(b-18) = 3g ----- (ii)
From, equations, (i) & (ii) => 4b - 72 = 3b => b=72 => Yesterday, the number of boys were 72 and today their number has reduced to (72-18) to 54.
Re: GRE Math Challenge #24-Yesterday, a certain school had
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08 Mar 2018, 00:48
08 Mar 2018, 00:48
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soumya1989 wrote:
Yesterday, a certain school had an equal number of boys and girls. Today, 18 boys left the school, and the ratio of the number of boys to girls is now 3 to 4.
A)The quantity in Column A is greater.
B)The quantity in Column B is greater.
C)The two quantities are equal.
D)The relationship cannot be determined from the information given.
| Column A | Column B |
| Number of boys in the school now | 72 |
A)The quantity in Column A is greater.
B)The quantity in Column B is greater.
C)The two quantities are equal.
D)The relationship cannot be determined from the information given.
First of all, we should set the ratio in terms of scale factor for the numbers of boy to girls yesterday. That is \(\frac{a}{a}\) where the numerator stands for boy.
For today we can set that \(\frac{a-18}{a}\)=\(\frac{3}{4}\).
Then we cross multiply. We get 3a=4a-72, a=72. and today's boy number would be 72-18=54
Thus, B>A
