City W and City X were 819 km apart. A sedan travelled from City W towards City X. At the same time, a van started from City X to City W. After travelling 1
15 h, the two vehicles were still 585 km apart. If the ratio of the average speed of the van to that of the sedan was 6 : 7, find
- the average speed of the van.
- the time taken for them to meet travelling the rest of the journey. Express your answer in h.
(a)
Distance covered in 1
15 h by the two vehicles
= 819 - 585
= 234 km
Combined speed of the two vehicles
= 234 ÷
65 = 234 x
56 = 195 km/h
Average speed of the van : Average speed of the sedan = 6 : 7
6 u + 7 u = 13 u
13 u = 195
1 u = 195 ÷ 13 = 15
Average speed of the van
= 6 u
= 6 x 15
= 90 km/h
(b)
Time taken for the van and the sedan to meet travelling the rest of the journey
= 585 ÷ 195
= 3 h
Answer(s): (a) 90 km/h; (b) 3 h