City G and City H were 550 km apart. A van travelled from City G towards City H. At the same time, a lorry started from City H to City G. After travelling 1
13 h, the two vehicles were still 330 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 lorry.
- the time taken for them to meet travelling the rest of the journey. Express your answer in h.
(a)
Distance covered in 1
13 h by the two vehicles
= 550 - 330
= 220 km
Combined speed of the two vehicles
= 220 ÷
43 = 220 x
34 = 165 km/h
Average speed of the lorry : Average speed of the van = 5 : 6
5 u + 6 u = 11 u
11 u = 165
1 u = 165 ÷ 11 = 15
Average speed of the lorry
= 5 u
= 5 x 15
= 75 km/h
(b)
Time taken for the lorry and the van to meet travelling the rest of the journey
= 330 ÷ 165
= 2 h
Answer(s): (a) 75 km/h; (b) 2 h