Ratios, Rates, Proportional Relationships, and Units Flashcards

A 24-oz bottle of shampoo costs $6.00 and a 40-oz bottle costs $9.20. How many more cents per ounce does the smaller bottle cost?

Answer: 2 cents/oz

Small: 600 ÷ 24 = 25 cents/oz; large: 920 ÷ 40 = 23 cents/oz; difference = 2 cents/oz.

A pipe leaks 2.4 liters per hour. How many liters does it leak in 4 days and 6 hours?

Answer: 244.8 liters

Total hours = (4 × 24) + 6 = 102 hours; leaked = 102 × 2.4 = 244.8 liters.

In a park, 5 out of every 8 visitors use the walking trail. On a day with 1,040 visitors, how many used the trail?

Answer: 650

5/8 × 1,040 = 650 visitors.

A car traveled 216 miles on 8 gallons of gas. At the same rate, how many gallons does it need to travel 351 miles?

Answer: 13 gallons

MPG = 216 ÷ 8 = 27; gallons for 351 miles = 351 ÷ 27 = 13 gallons.

A student scored 78, 85, 92, and 79 on four tests. What score on the fifth test gives an average of exactly 85?

Answer: 91

Total needed = 85 × 5 = 425; current total = 78 + 85 + 92 + 79 = 334; fifth score = 425 − 334 = 91.

Workers A and B together earn $1,800 per week. Worker A earns $200 more per week than Worker B. How much does Worker B earn per week?

Answer: $800

Let B = x; A = x + 200; x + (x + 200) = 1,800; 2x = 1,600; x = $800.

A 15-liter radiator coolant mixture is 40% antifreeze. How many liters of pure antifreeze must be added to make a 60% antifreeze mixture?

Answer: 7.5 liters

Current antifreeze = 0.40 × 15 = 6 L; let x = liters added; (6 + x)/(15 + x) = 0.60; 6 + x = 9 + 0.60x; 0.40x = 3; x = 7.5 liters.