At 7 a.m., Luis started from City N and travelled towards City P and his speed remained constant throughout. At 9 a.m., Shiyun started her journey from City N towards City P at an average speed of 72 km/h. Shiyun overtook Luis at 1 p.m. After overtaking, Shiyun carried on her journey at the same average speed and reached at City P at 2:30 p.m.
- Find Luis's average speed in km/h.
- What is the distance between the two cities?
(a)
From 9 a.m. to 1 p.m. = 4 h
Distance that Shiyun had travelled until Shiyun overtook Luis
= 4 x 72
= 288 km
From 7 a.m. to 1 p.m. = 6 h
Luis's average speed
= 288 ÷ 6
= 48 km/h
(b)
From 9 a.m. to 2:30 p.m. = 5 h 30 min
1 h = 60 min
5 h 30 min = 5
30 60
h = 5
12 h
Distance between the two cities
= 5
12 x 72
=
112 x 72
= 396 km
Answer(s): (a) 48 km/h; (b) 396 km