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.
The ratio of the number of boys to the number of girls in
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One approach: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
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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Another approach: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
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
Cheers,
Brent
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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
GMAT assassins aren't born, they're made,
Rich
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
GMAT assassins aren't born, they're made,
Rich
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We can create the ratio boys : girls = 3x : 4x and create the equation: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
3x + 5 = 4x
5 = x
So there are 4 x 5 = 20 girls in the club.
Answer: E
Jeffrey Miller
Head of GMAT Instruction
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