At 8 a.m., Lee started from City U and travelled towards City V and his speed remained constant throughout. At 10 a.m., Min started her journey from City U towards City V at an average speed of 90 km/h. Min overtook Lee at 2 p.m. After overtaking, Min carried on her journey at the same average speed and reached at City V at 5:30 p.m.
- Find Lee's average speed in km/h.
- What is the distance between the two cities?
(a)
From 10 a.m. to 2 p.m. = 4 h
Distance that Min had travelled until Min overtook Lee
= 4 x 90
= 360 km
From 8 a.m. to 2 p.m. = 6 h
Lee's average speed
= 360 ÷ 6
= 60 km/h
(b)
From 10 a.m. to 5:30 p.m. = 7 h 30 min
1 h = 60 min
7 h 30 min = 7
30 60
h = 7
12 h
Distance between the two cities
= 7
12 x 90
=
152 x 90
= 675 km
Answer(s): (a) 60 km/h; (b) 675 km