Problem Solving

The ratio of the number of boys to the number of girls in a certain school club is 3 : 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

B/G = 3/4

B= 3G/4 (1)

Given B+5 = G

Substitute for B) FROM (1)

3G/4+5=G

G=20

E)

bacali wrote:The ratio of the number of boys to the number of girls in a certain school club is 3 : 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

work from options

Girls=20; Boys 15 ( since girls are more by 5)

Ratio: 3/4 satisfies data

hence E


You can quickly do this

A. 7 Girls........................Boys.7-5 (2)........ Ratio 2/7 Incorrect
B. 8.......................................8-5(3)........... Ratio 3/8 Incorrect
C. 12......................................7..................7/12 Incorrect
D. 15.....................................10...................2/3 Incorrect
E. 20[/quote]..........................15...................3/4 Correct


This is not always required...I was just looking for a no in the options...which is multiple of 5 (after you deduct 5 )

Only last 2 fit the bills...hence I worked only D and E

and quicky got E

bacali wrote:The ratio of the number of boys to the number of girls in a certain school club is 3 : 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

My 2 cents...

Boy/Girls : 3/4 ( I love the ratio by the way) , so GIRL's number:

Needs to be divided by 4

A and D are gone. GMAC will always put the boys number to fool you, in case you miss something and we know GIRL-BOY = 5 and GIRL's number are bigger.

If you look at the options 7 and 12 ( 5 apart )

15 and 20 ( 5 apart )

and there is a dummy 8! with no pair there is no 13 or 3 i the options.

remaining options: 20 and 12

well 12 was the GIRLS number for 7
and 20 was the GIRLS number for 15

so I feel like it is 20

and I just double check:

B/G = 3/4 = B/20 ===> B =15

G-B = 5 BINGO!

I just wanted to give you a different insight. Hope it helps!

Boys:3x
Girls:4x

4x=3x+5
x=5

Total # of girls: 4(5)=20

My 2 cents...

Ratio B:G is 3:4... so total parts 7 (3+4)
Difference in ratio is 1/7 i.e (4-3)/7 which is given as 5
And girls are 4 parts of 7 i.e 4(1/7) = 4*5 = 20

Ratio is 3:4 Boys to Girls
There is a difference of +1 girls in the ratio...just multiply both boys and girls by 5 and you get your answer... 15 boys 20 girls