Rates Flashcards
What is a rate?
A rate is used to compare quantities that have different units, for example kilometres and hours. It is useful to think of rate as ‘how many of a given quantity for every unit of another quantity.’
Give three examples of rates.
- The speed of a car: 50km/h
- The petrol used by the car: 15km/litre
- Exchange rate: R12/ £1.
(£ is a British pound, btw.)
Calculate.
In a science experiment, the temperature increased steadily from 12 degrees C to 77 degrees C in five minutes. Calculate the rate of temperature increase per minute.
We need to calculate how much the temperature rises every minute.
Increase in temperature over the total time period= 77-12= 65 degrees C.
Total time period: 5 minutes.
The rate of temperature increase is 65 divided by 5 = 13 degrees C.
Calculate.
A car travels 180km from Mooi River along the N3 high way to the South Coast. It takes the driver four hours. Determine the average speed of the car in km/h.
We want to find the distance travelled in one unit of time (an hour).
The average speed will be = 180 divided by 4 = 45
=45km/hour
Calculate.
A painter normally gets paid R80 per hour and gets R120 per hour for overtime. One painter works 52 hours normal time and 8 hours on a particular job. Calculate how much she will get paid.
For 52 hours of normal time, the painter gets paid:
52 x 80 = R4160
For 8 hours of overtime, she gets paid:
8 x 120 = R960
Total amount paid for the job: 4160 + 960 = R5120
Calculate. (Answer not provided since the textbook didn’t give one… use a piece of paper and such idk)
A car uses 40 litres of petrol to drive 500 km. Calculate petrol consumption in km/l.
= ?
Calculate. (Answer not provided since the textbook didn’t give one… use a piece of paper and such idk)
A car drives 740km from PE to Joburg in 9 hours. Calculate the average speed.
= ?
For more practise questions, refer to page 15-16 of our textbooks.
Yes ma’am o7
