Bluebook SAT Test Ratios, Rates, Proportional Relationships, and Units 8

Question 1

A painting crew can paint a house in 6 days working 8 hours a day. How many days would it take if they worked 12 hours a day instead?

Accepted Answer

4

Answer

Total hours = 6 × 8 = 48; at 12 hr/day: 48 ÷ 12 = 4 days.

Question 2

Oil and vinegar are mixed in a ratio of 2:5 in a salad dressing. If the total volume is 280 mL, how many mL of oil are in the dressing?

Accepted Answer

80 mL

Answer

Oil fraction = 2/7; oil = (2/7) × 280 = 80 mL.

Question 3

A car's fuel efficiency is 32 miles per gallon. If gas costs $3.60 per gallon, what is the fuel cost for a 400-mile trip?

Accepted Answer

$45.00

Answer

Gallons needed = 400 ÷ 32 = 12.5; cost = 12.5 × $3.60 = $45.00.

Question 4

The ratio of red marbles to blue marbles is 3:2. If 5 red marbles are added, the ratio becomes 2:1. How many blue marbles are there?

Accepted Answer

10

Answer

Let red = 3x and blue = 2x; (3x+5)/(2x) = 2 → 3x+5 = 4x → x = 5; blue = 2×5 = 10.

Question 5

If 1 foot = 30.48 cm, what is 5 yards in centimeters? (1 yard = 3 feet)

Accepted Answer

457.2 cm

Answer

5 yards = 15 feet = 15 × 30.48 = 457.2 cm.

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