At 7 a.m., Luke started from City L and travelled towards City M and his speed remained constant throughout. At 9 a.m., Sarah started her journey from City L towards City M at an average speed of 69 km/h. Sarah overtook Luke at 1 p.m. After overtaking, Sarah carried on her journey at the same average speed and reached at City M at 4:40 p.m.
- Find Luke'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 Sarah had travelled until Sarah overtook Luke
= 4 x 69
= 276 km
From 7 a.m. to 1 p.m. = 6 h
Luke's average speed
= 276 ÷ 6
= 46 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 69
=
233 x 69
= 529 km
Answer(s): (a) 46 km/h; (b) 529 km