GMAT Quantitative: Ratios and Proportions 2

Question 1

The ratio of cats to dogs in a shelter is 5:3. If there are 40 animals total, how many are dogs?

Accepted Answer

15

Answer

Total parts = 5+3 = 8, so each part = 40/8 = 5, and dogs = 3 x 5 = 15.

Question 2

If a/b = 4/7, what is the value of (a+b)/b?

Accepted Answer

11/7

Answer

(a+b)/b = a/b + 1 = 4/7 + 7/7 = 11/7.

Question 3

Two numbers are in the ratio 3:5 and their sum is 64. What is the larger number?

Accepted Answer

40

Answer

Each part = 64/8 = 8, so the larger number = 5 x 8 = 40.

Question 4

A recipe uses flour and sugar in the ratio 7:2. To make a batch with 21 cups of flour, how much sugar is needed?

Accepted Answer

6 cups

Answer

21/7 = 3 scaling factor, so sugar = 2 x 3 = 6 cups.

Question 5

If 12 workers can build a wall in 10 days, how many days would 15 workers take (inverse proportion)?

Accepted Answer

8

Answer

Work = 12 x 10 = 120 worker-days, so 120/15 = 8 days.

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