At 08 20, Kathy left Town Z and cycled towards Town A. Mary left Town Z and cycled towards Town A at 08 40. Mary's cycling speed was 6 km/h faster than Kathy. At 10 20, Mary caught up with Kathy. Find the cycling speed of each cyclist.
- Kathy
- Mary
(a)
Duration that Mary cycled from 08 40 to 10 20
= 1
4060 = 1
23 h
Distance that Mary cycled more than Kathy
= 1
23 x 6
= 10 km
However, since Kathy left 20 minutes earlier than Mary and Mary caught up with Kathy, it means that Kathy has cycled 10 km in 20 min.
1 h = 60 min
20 min = 20 ÷ 60 =
13 h
Kathy's cycling speed
= 10 ÷
13 = 10 x
31 = 30 km/h
(b)
Mary's cycling speed
= 30 + 6
= 36 km/h
Answer(s): (a) 30 km/h ; (b) 36 km/h
