# Proportion and speed

> Grade 8: direct proportion, unitary method, best buy comparisons, speed = distance / time, units of speed.

Source: https://olyclass.com/library/math-g8-proportion-speed-en/

- Subject: Math
- Level: Grade 8
- Practice: 16
- Play it free on one screen (projector, TV or whiteboard): https://olyclass.com/library?play=math-g8-proportion-speed-en
- Copy and edit it: https://olyclass.com/library?copy=math-g8-proportion-speed-en
- Games it plays well in: [Penalty Kick](https://olyclass.com/classroom-games/penalty-kick/), [Fishing Pond](https://olyclass.com/classroom-games/fishing-pond/), [Claw Machine](https://olyclass.com/classroom-games/claw-machine/), [Lucky Drop](https://olyclass.com/classroom-games/lucky-drop/)

## Questions

1. If 3 pens cost $6 and the price is in direct proportion, how much do 5 pens cost? ($10 / $12 / $15 / $8)
   Answer: $10
2. If two quantities are in direct proportion, doubling one doubles the other.
   Answer: True
3. A recipe uses 200 g flour for 4 people. How much flour for 10 people? (450 g / 500 g / 550 g / 800 g)
   Answer: 500 g
4. Which pair of values is in direct proportion? (1 : 3 and 4 : 10 / 1 : 3 and 4 : 12 / 2 : 5 and 4 : 9 / 3 : 6 and 5 : 9)
   Answer: 1 : 3 and 4 : 12
5. 8 notebooks cost $24. Using the unitary method, what is the cost of one notebook? ($16 / $2 / $3 / $4)
   Answer: $3
6. 7 identical apples weigh 560 g. What do 12 apples weigh, in grams?
   Answer: 960 g
7. Which is the better buy? A: 5 kg for $10. B: 3 kg for $7.50. (A / B / Both are the same / Cannot tell)
   Answer: A
8. Juice: 500 ml costs $1.20 and 2 litres costs $4.00. Which is cheaper per litre? (Cannot tell / The 2 litre bottle / The 500 ml bottle / They cost the same)
   Answer: The 2 litre bottle
9. A car travels 150 km in 3 hours. What is its average speed? (153 km/h / 30 km/h / 450 km/h / 50 km/h)
   Answer: 50 km/h
10. A cyclist riding at 12 km/h for 2.5 hours travels 30 km.
   Answer: True
11. A train goes at 80 km/h. How long does it take to travel 200 km? (16 hours / 2 hours / 2.5 hours / 3 hours)
   Answer: 2.5 hours
12. A runner covers 600 m in 2 minutes. What is her speed in metres per minute?
   Answer: 300 m/min
13. Which unit is most suitable for the speed of a snail? (cm per minute / kg per hour / km per hour / m per second squared)
   Answer: cm per minute
14. A speed of 36 km/h is the same as 20 m/s.
   Answer: False
15. Convert 10 m/s into km/h. (10 km/h / 100 km/h / 3.6 km/h / 36 km/h)
   Answer: 36 km/h
16. A bus drives 45 km in 45 minutes. What is its speed in km/h?
   Answer: 60 km/h