City M and City N were 572 km apart. A van travelled from City M towards City N. At the same time, a lorry started from City N to City M. After travelling 1
14 h, the two vehicles were still 352 km apart. If the ratio of the average speed of the lorry to that of the van was 5 : 6, 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
14 h by the two vehicles
= 572 - 352
= 220 km
Combined speed of the two vehicles
= 220 ÷
54 = 220 x
45 = 176 km/h
Average speed of the lorry : Average speed of the van = 5 : 6
5 u + 6 u = 11 u
11 u = 176
1 u = 176 ÷ 11 = 16
Average speed of the van
= 6 u
= 6 x 16
= 96 km/h
(b)
Time taken for the lorry and the van to meet travelling the rest of the journey
= 352 ÷ 176
= 2 h
Answer(s): (a) 96 km/h; (b) 2 h