Primary 5 Rate
Keywords
- Rate
- An amount of one quantity per unit of another quantity.
- Per
- For each one.
- Unit
- The measure used for a quantity, such as hour, kilogram or litre.
- Unit rate
- The amount for one unit, such as 8 km per hour.
What a rate tells us
A rate compares two quantities with different units. The word “per” tells us the amount for each one unit.
See worked example
A van travels 24 km in 3 hours. What does 8 km per hour mean?
It means the van travels 8 km in each 1 hour, at this rate.
Answer: 8 km for every 1 hour.
Try together
What does $4 per kilogram mean?
Reveal the answer
Each 1 kg costs $4.
Amount per unit
A rate is the amount of one quantity per unit of another quantity. Share the total equally among the units to see the amount for one unit.
Choose an example
Try together
Four identical notebooks cost $28. What is the cost per notebook?
Reveal the answer
$28 ÷ 4 = $7 per notebook.
Find the rate
Divide the first quantity by the number of units in the second quantity. Check that its unit matches the “per” unit in the answer.
Choose a question
See worked example
A tap gives 90 ℓ of water in 1 hour 30 minutes. Find the rate in litres per minute.
- 1 hour 30 minutes = 90 minutes.
- 90 ℓ ÷ 90 minutes = 1 ℓ per minute.
Answer: 1 ℓ per minute.
Try together
A cyclist travels 48 km in 4 hours. Find the rate in kilometres per hour.
Reveal the answer
48 km ÷ 4 hours = 12 km per hour.