At 09 15, Mary left Town X and cycled towards Town Y. Xuan left Town X and cycled towards Town Y at 09 45. Xuan's cycling speed was 4 km/h faster than Mary. At 13 15, Xuan caught up with Mary. Find the cycling speed of each cyclist.
- Mary
- Xuan
(a)
Duration that Xuan cycled from 09 45 to 13 15
= 3
3060 = 3
12 h
Distance that Xuan cycled more than Mary
= 3
12 x 4
= 14 km
However, since Mary left 30 minutes earlier than Xuan and Xuan caught up with Mary, it means that Mary has cycled 14 km in 30 min.
1 h = 60 min
30 min = 30 ÷ 60 =
12 h
Mary's cycling speed
= 14 ÷
12 = 14 x
21 = 28 km/h
(b)
Xuan's cycling speed
= 28 + 4
= 32 km/h
Answer(s): (a) 28 km/h ; (b) 32 km/h
