Idea 18of 22Builds onThe unit rate is the amount for one
Use the unit rate for any amount
How far does the train go in 5 hours?
Today you'll discover
- why 5 hours is not a jump of 3
- how to go down to one and back up
- when a rate can be scaled
Think first240 km in 3 hours. What about 5 hours?
5 hours is not a jump of 3 hours. How far does the train go in 5 hours?
Decide first, then press Next. Go down to 1, then up to the amount you want.
Two number lines, hours on top and kilometres below, with ticks at 3 hours and 240 km and 6 hours and 480 km. Then a green tick at 1 hour and 80 km. Then a ringed tick at 5 hours and 400 km, joined across. The last step shows a cyclist, 45 km in 3 hours, and asks about 4 hours.
See the whole ideathe big idea and the key word, in one place
The big idea
At a constant rate, multiply the unit rate to find any amount.
Down to one, up to any
240 km in 3 hours, ÷ 3, is 80 km in 1 hour; × 5, that is 400 km in 5 hours.
- 3 hours240 km
- 1 hour80 km
- 5 hours400 km
Easy to get wrongA real train speeds up and slows down. “At the same rate” is what lets you scale; without it, the answer is only an estimate.
Key word
- constant rate
- a rate that stays the same the whole time, so it can be scaled up or down
Ready to use it?
- Use a unit rate to find any amount.
- Solve a rate problem that is not a whole jump.