What a rate means
A rate compares how much one quantity changes for each unit of another.
A rate tells you how one quantity changes compared with another. You meet rates every day, often without noticing:
- A car travels at km per hour — that is distance compared with time.
- Apples cost \3$ per kilogram — that is cost compared with weight.
- You type words per minute — that is words compared with time.
The word per is the giveaway — it means "for each". A rate of km per hour means that for each hour, km is covered.
A rate always has compound units — two units joined together, like km/h or $/kg. The slash also means "per".
Rates are powerful because they let you predict. If you know a steady rate, you can work out the total for any amount of time, weight or quantity.
- A rate compares how one quantity changes with another.
- The word 'per' means 'for each'.
- Rates have compound units like km/h or $/kg.
- A known rate lets you predict totals.