Bluebook SAT Test Ratios, Rates, Proportional Relationships, and Units 14

Question 1

A store sells cereal in two sizes: 400 g for $3.20 and 600 g for $4.50. Which box has the better unit price per 100 g?

Accepted Answer

600 g box at $0.75 per 100 g

Answer

400 g box: $3.20/4 = $0.80 per 100 g; 600 g box: $4.50/6 = $0.75 per 100 g; 600 g is cheaper.

Question 2

A mechanic charges $45 per hour plus a flat fee of $30. If a customer's total bill is $210, how many hours did the mechanic work?

Accepted Answer

4 hours

Answer

45h + 30 = 210; 45h = 180; h = 4 hours.

Question 3

A train and a car leave the same city heading in the same direction. The train travels at 80 mph and the car at 50 mph. After 3 hours, how many miles apart are they?

Accepted Answer

90 miles

Answer

Relative speed = 80 − 50 = 30 mph; distance apart = 30 × 3 = 90 miles.

Question 4

A recipe uses milk and water in the ratio 3:1 to make a total of 2 liters. How many mL of water are needed? (1 L = 1,000 mL)

Accepted Answer

500 mL

Answer

Water fraction = 1/(3+1) = 1/4; water = 1/4 × 2,000 mL = 500 mL.

Question 5

A car accelerates from 0 to 60 mph in 8 seconds. What is the car's average acceleration in mph per second?

Accepted Answer

7.5 mph/s

Answer

Acceleration = (60 − 0) ÷ 8 = 7.5 mph per second.

Bluebook SAT Practice Test

Bluebook SAT Practice Test

Bluebook SAT Test Ratios, Rates, Proportional Relationships, and Units 14