City W and City X were 728 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
12 h, the two vehicles were still 416 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 sedan.
- the time taken for them to meet travelling the rest of the journey. Express your answer in h.
(a)
Distance covered in 1
12 h by the two vehicles
= 728 - 416
= 312 km
Combined speed of the two vehicles
= 312 ÷
32 = 312 x
23 = 208 km/h
Average speed of the van : Average speed of the sedan = 6 : 7
6 u + 7 u = 13 u
13 u = 208
1 u = 208 ÷ 13 = 16
Average speed of the sedan
= 7 u
= 7 x 16
= 112 km/h
(b)
Time taken for the van and the sedan to meet travelling the rest of the journey
= 416 ÷ 208
= 2 h
Answer(s): (a) 112 km/h; (b) 2 h