Bluebook SAT Test Ratios, Rates, Proportional Relationships, and Units 7

Question 1

A hose fills a 2,400-gallon pool in 8 hours. A second hose fills it in 12 hours. How many hours will it take both hoses together to fill the pool?

Accepted Answer

4.8 hr

Answer

Combined rate = 1/8 + 1/12 = 5/24 pools/hr; time = 24/5 = 4.8 hours.

Question 2

A wheel has a radius of 35 cm. How many full rotations does the wheel make when it travels 440 meters? (Use π ≈ 22/7)

Accepted Answer

200

Answer

Circumference = 2 × (22/7) × 35 = 220 cm = 2.2 m; rotations = 440 ÷ 2.2 = 200.

Question 3

A recipe requires 2.5 cups of milk for every 3 cups of flour. If a chef has 9 cups of flour, how many cups of milk are needed?

Accepted Answer

7.5

Answer

Milk = (2.5/3) × 9 = 7.5 cups.

Question 4

A town's population grows at a constant rate. Its population was 15,000 in 2010 and 18,000 in 2015. What will the population be in 2020 at this rate?

Accepted Answer

21,000

Answer

Growth = 3,000 per 5 years; 2020 population = 18,000 + 3,000 = 21,000.

Question 5

A metal pipe is 4 meters long and weighs 24 kg. What is the weight, in kg, of a pipe of the same material that is 6.5 meters long?

Accepted Answer

39 kg

Answer

Weight per meter = 24 ÷ 4 = 6 kg/m; weight = 6 × 6.5 = 39 kg.

Bluebook SAT Practice Test