Unit Rates & Better Buys — Practice
Reduce everything to one of something, and comparisons become obvious.
What these questions cover
These questions use 2 ideas from the course. Follow any of them for a definition, where it is taught, and what it leads to.
- Rate — A ratio of two different units, like miles per hour or dollars per pound.
- Better buy — The option with the lower unit price.
Problem 1
A car travels 210 miles in 3 hours. Find the speed in miles per hour.
Worked answer
70
210 ÷ 3 = 70
Problem 2
A printer prints 180 pages in 4 minutes. Find the rate per minute.
Worked answer
45
180 ÷ 4 = 45
Problem 3
A 12 oz jar costs $3.00. Find the price per ounce.
Worked answer
0.25
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Problem 4
A 5 kg bag costs $8.50. Find the price per kilogram.
Worked answer
1.7
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Problem 5
How many centimetres are in 2.5 metres?
Worked answer
250
2.5 × 100 = 250
Problem 6
A 12 oz jar is $3.00; an 18 oz jar is $4.05. Which is the better buy?
- The 18 oz jar
- The 12 oz jar
- They are the same
- Cannot tell
Worked answer
The 18 oz jar
0.25 against 0.225 per ounce
Problem 7
At 70 mph, how far in 5 hours?
Worked answer
350
70 × 5 = 350
Problem 8
A tap fills 8 litres per minute. How long to fill 120 litres?
Worked answer
15
120 ÷ 8 = 15 minutes
Problem 9
6 apples cost $2.70. What do 10 cost?
Worked answer
4.5
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Problem 10
How many inches are in 4 feet?
Worked answer
48
4 × 12 = 48
Problem 11
How many metres are in 350 centimetres?
Worked answer
3.5
350 ÷ 100 = 3.5
Problem 12
Someone earns $102 for 8 hours. What is the hourly rate?
Worked answer
12.75
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Problem 13
Runner A does 5 km in 25 minutes. Runner B does 8 km in 36 minutes. How many minutes per km for B?
Worked answer
4.5
36 ÷ 8 = 4.5
Problem 14
A car uses 45 litres for 540 km. How many km per litre?
Worked answer
12
540 ÷ 45 = 12
Problem 15
A recipe for 4 people uses 600 g of rice. How much for 7 people?
Worked answer
1050
600 ÷ 4 = 150 g each
150 × 7 = 1050 g
Problem 16
At $0.45 per apple, how many apples for $5.40?
Worked answer
12
5.40 ÷ 0.45 = 12