At 9 a.m., Luke started from City P and travelled towards City Q and his speed remained constant throughout. At 10 a.m., Xandra started her journey from City P towards City Q at an average speed of 84 km/h. Xandra overtook Luke at 1 p.m. After overtaking, Xandra carried on her journey at the same average speed and reached at City Q at 5:50 p.m.
- Find Luke's average speed in km/h.
- What is the distance between the two cities?
(a)
From 10 a.m. to 1 p.m. = 3 h
Distance that Xandra had travelled until Xandra overtook Luke
= 3 x 84
= 252 km
From 9 a.m. to 1 p.m. = 4 h
Luke's average speed
= 252 ÷ 4
= 63 km/h
(b)
From 10 a.m. to 5:50 p.m. = 7 h 50 min
1 h = 60 min
7 h 50 min = 7
50 60
h = 7
56 h
Distance between the two cities
= 7
56 x 84
=
476 x 84
= 658 km
Answer(s): (a) 63 km/h; (b) 658 km