At 9 a.m., John started from City K and travelled towards City L and his speed remained constant throughout. At 10 a.m., Tina started her journey from City K towards City L at an average speed of 72 km/h. Tina overtook John at 3 p.m. After overtaking, Tina carried on her journey at the same average speed and reached at City L at 4:20 p.m.
- Find John's average speed in km/h.
- What is the distance between the two cities?
(a)
From 10 a.m. to 3 p.m. = 5 h
Distance that Tina had travelled until Tina overtook John
= 5 x 72
= 360 km
From 9 a.m. to 3 p.m. = 6 h
John's average speed
= 360 ÷ 6
= 60 km/h
(b)
From 10 a.m. to 4:20 p.m. = 6 h 20 min
1 h = 60 min
6 h 20 min = 6
20 60
h = 6
13 h
Distance between the two cities
= 6
13 x 72
=
193 x 72
= 456 km
Answer(s): (a) 60 km/h; (b) 456 km