At 09 20, Risa left Town W and cycled towards Town X. Sarah left Town W and cycled towards Town X at 09 50. Sarah's cycling speed was 4 km/h faster than Risa. At 13 20, Sarah caught up with Risa. Find the cycling speed of each cyclist.
- Risa
- Sarah
(a)
Duration that Sarah cycled from 09 50 to 13 20
= 3
3060 = 3
12 h
Distance that Sarah cycled more than Risa
= 3
12 x 4
= 14 km
However, since Risa left 30 minutes earlier than Sarah and Sarah caught up with Risa, it means that Risa has cycled 14 km in 30 min.
1 h = 60 min
30 min = 30 ÷ 60 =
12 h
Risa's cycling speed
= 14 ÷
12 = 14 x
21 = 28 km/h
(b)
Sarah's cycling speed
= 28 + 4
= 32 km/h
Answer(s): (a) 28 km/h ; (b) 32 km/h
