At 09 20, Sarah left Town X and cycled towards Town Y. Kathy left Town X and cycled towards Town Y at 09 50. Kathy's cycling speed was 6 km/h faster than Sarah. At 11 20, Kathy caught up with Sarah. Find the cycling speed of each cyclist.
- Sarah
- Kathy
(a)
Duration that Kathy cycled from 09 50 to 11 20
= 1
3060 = 1
12 h
Distance that Kathy cycled more than Sarah
= 1
12 x 6
= 9 km
However, since Sarah left 30 minutes earlier than Kathy and Kathy caught up with Sarah, it means that Sarah has cycled 9 km in 30 min.
1 h = 60 min
30 min = 30 ÷ 60 =
12 h
Sarah's cycling speed
= 9 ÷
12 = 9 x
21 = 18 km/h
(b)
Kathy's cycling speed
= 18 + 6
= 24 km/h
Answer(s): (a) 18 km/h ; (b) 24 km/h
