GMAT advanced Maths

Question 1

GMATAdvanced GMAT Math QuestionsVersion 2
Quantitative –Fractions and Ratios21. EAnswers1. The current ratio of boys to girls at a certain school is 2to 5. If 12 additional boys were added to the school, the new ratio of boys to girls would be 4 to 9. How many boys currently attend the school?

Answer 1

5b=2g
9(b+12)=4g
9b+108=10b
B=108

Question 2

108GMAT
Quantitative –Work3(A) 1 (B) 5(C) 7(D) 25(E) 351. If 7 workers can build 7 cars in 7 days, then how many days would it take 5 workers to build 5 cars? (A) 28 (B) 30(C) 32(D) 36(E) 403.

Answer 2

If 7 workers are building 7 cars in 7 days then
7 workers are building 7/7= 1 car per day
Therefore each worker is building 1/7 car per day

Then 5 workers are building 5/7 cars per day

Then to build 5 cars

Ratetime = work
5/7t =5
T=57/5= 7 days

Question 3

Bea can paint a house three times faster than Alice can paint a house. If, working together, it takes Alice and Bea 24 hours to paint a house, then how many hours will it take Bea to paint a house alone?2.

Answer 3

C

Alice and Bea 24 hours to paint a house: means that in 1 hr they will complete 1/24th of the work.

Bea can paint a house three times faster than Alice can paint a house: Means that if alice takes t time to complete a work Bea will take (1/3) t to complete same work.

Alice - takes t time to complete 1 work - in 1 hr it will do - 1/t work

Bea- takes (1/3)t time to complete the same work- in 1 hr it will do- 1/(t/3) work= 3/t work

1/t+ 3/t = 1/24

Solving this we get t=96. So bea will take 1/3 *96 = 32 hrs to do the work.

So C.

Question 4

If 6 workers can build 4 cars in 2 days, then how many days would it take 8 workers to build 6 cars?

Answer 4

B

6 workers can build 4 cars in 2 days.
1 worker can build 4 cars in 26 = 12 days
1 worker can build 1 car in 12/4 = 3 days
1 worker can build 6 cars in 36 = 18 days
8 workers can build 6 cars in 18/8 = 9/4 days

The correct answer is (B).

Question 5

What percent of 15 is 15 percent of 1? 1. DAnswersGMAT

Quantitative –Integer Properties5(A) 0(B) 1(C) 2(D) 3(E) 4 2.

Answer 5

B

15% of 1 is 0.15
0.15 is 1% of 15
Hence B is the answer