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The ratio of the number of boys to the number of girls in

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by Gmat_mission » Sat Mar 17, 2018 9:19 am
The ratio of the number of boys to the number of girls in a certain school club is 3 to 4. if there are 5 more girls than boys in the club, how many girls are in the club?

A. 7
B. 8
C. 12
D. 15
E. 20

[spoiler]OA=E[/spoiler].

What is the best approach that can be used to solve this PS question? Experts, I'd be thankful for your help.
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by Brent@GMATPrepNow » Sat Mar 17, 2018 5:14 pm
Gmat_mission wrote:The ratio of the number of boys to the number of girls in a certain school club is 3 to 4. if there are 5 more girls than boys in the club, how many girls are in the club?

A. 7
B. 8
C. 12
D. 15
E. 20
One approach:

The ratio of the number of boys to the number of girls in a certain school club is 3 to 4.
So, some possible scenarios are:

3 boys and 4 girls
6 boys and 8 girls
9 boys and 12 girls
.
.
.
There are 5 more girls than boys in the club
So, keep listing scenarios until we have 5 more girls than boys
.
.
12 boys and 16 girls (there are 4 more girls that boys)
15 boys and 20 girls (there are 5 more girls that boys) BINGO!!

Answer: E

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Brent
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by Brent@GMATPrepNow » Sat Mar 17, 2018 5:16 pm
Gmat_mission wrote:The ratio of the number of boys to the number of girls in a certain school club is 3 to 4. if there are 5 more girls than boys in the club, how many girls are in the club?

A. 7
B. 8
C. 12
D. 15
E. 20
Another approach:

There are 5 more girls than boys in the club
Let G = # of girls in club
So G-5 = # of boys in club

The ratio of the number of boys to the number of girls in a certain school club is 3 to 4.
We can write (G-5)/G = 3/4
Cross multiply: 4(G-5) = 3G
Expand: 4G - 20 = 3G
Solve: G = 20

Answer: E

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Brent
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by [email protected] » Sat Mar 17, 2018 7:03 pm
Hi Gmat_mission,

We're told that the ratio of the number of boys to the number of girls in a certain school club is 3 to 4 and that there are 5 more girls than boys in the club. We're asked for the number of girls in the club. This question can be solved in a variety of different ways, including by TESTing THE ANSWERS.

Since the ratio is 3 to 4, the number of boys is a multiple of 3 and the number of girls is an equivalent multiple of 4. Thus, the correct answer must be either B, C or E. In addition, for every 3 boys, there will be one additional girl. With a difference of 5, it's likely that the number of girls is also a multiple of 5. Let's TEST Answer E first.

Answer E: 20 girls
IF there are 20 girls - and 20 = (5)(4)....
there are (5)(3) = 15 boys
20 girls and 15 boys is a difference of 20 - 15 = 5 girls
This is an exact match for what we were told, so this must be the answer.

Final Answer: E

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by Jeff@TargetTestPrep » Wed Mar 21, 2018 3:26 pm
Gmat_mission wrote:The ratio of the number of boys to the number of girls in a certain school club is 3 to 4. if there are 5 more girls than boys in the club, how many girls are in the club?

A. 7
B. 8
C. 12
D. 15
E. 20
We can create the ratio boys : girls = 3x : 4x and create the equation:

3x + 5 = 4x

5 = x

So there are 4 x 5 = 20 girls in the club.

Answer: E

Jeffrey Miller
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by Gmat_mission » Sat Mar 24, 2018 4:38 am
Thank you all for your help.
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