Flashcards in GMAT advanced Maths Deck (5):

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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?

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5b=2g

9(b+12)=4g

9b+108=10b

B=108

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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.

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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

Rate*time = work

5/7t =5

T=5*7/5= 7 days

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## 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.

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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.

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

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B

6 workers can build 4 cars in 2 days.

1 worker can build 4 cars in 2*6 = 12 days

1 worker can build 1 car in 12/4 = 3 days

1 worker can build 6 cars in 3*6 = 18 days

8 workers can build 6 cars in 18/8 = 9/4 days

The correct answer is (B).

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