City R and City S were 627 km apart. A car travelled from City R towards City S. At the same time, a lorry started from City S to City R. After travelling 1
34 h, the two vehicles were still 396 km apart. If the ratio of the average speed of the lorry to that of the car 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
34 h by the two vehicles
= 627 - 396
= 231 km
Combined speed of the two vehicles
= 231 ÷
74 = 231 x
47 = 132 km/h
Average speed of the lorry : Average speed of the car = 5 : 6
5 u + 6 u = 11 u
11 u = 132
1 u = 132 ÷ 11 = 12
Average speed of the lorry
= 5 u
= 5 x 12
= 60 km/h
(b)
Time taken for the lorry and the car to meet travelling the rest of the journey
= 396 ÷ 132
= 3 h
Answer(s): (a) 60 km/h; (b) 3 h