At 7 a.m., Zeph started from City R and travelled towards City S and his speed remained constant throughout. At 9 a.m., Hazel started her journey from City R towards City S at an average speed of 90 km/h. Hazel overtook Zeph at 1 p.m. After overtaking, Hazel carried on her journey at the same average speed and reached at City S at 4:40 p.m.
- Find Zeph'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 Hazel had travelled until Hazel overtook Zeph
= 4 x 90
= 360 km
From 7 a.m. to 1 p.m. = 6 h
Zeph's average speed
= 360 ÷ 6
= 60 km/h
(b)
From 9 a.m. to 4:40 p.m. = 7 h 40 min
1 h = 60 min
7 h 40 min = 7
40 60
h = 7
23 h
Distance between the two cities
= 7
23 x 90
=
233 x 90
= 690 km
Answer(s): (a) 60 km/h; (b) 690 km