At 7 a.m., Zeph started from City A and travelled towards City B and his speed remained constant throughout. At 8 a.m., Yen started her journey from City A towards City B at an average speed of 84 km/h. Yen overtook Zeph at 1 p.m. After overtaking, Yen carried on her journey at the same average speed and reached at City B at 3:30 p.m.
- Find Zeph's average speed in km/h.
- What is the distance between the two cities?
(a)
From 8 a.m. to 1 p.m. = 5 h
Distance that Yen had travelled until Yen overtook Zeph
= 5 x 84
= 420 km
From 7 a.m. to 1 p.m. = 6 h
Zeph's average speed
= 420 ÷ 6
= 70 km/h
(b)
From 8 a.m. to 3:30 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 84
=
152 x 84
= 630 km
Answer(s): (a) 70 km/h; (b) 630 km