City D and City E were 540 km apart. A sports car travelled from City D towards City E. At the same time, a lorry started from City E to City D. After travelling 1
34 h, the two vehicles were still 288 km apart. If the ratio of the average speed of the lorry to that of the sports car was 4 : 5, 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
= 540 - 288
= 252 km
Combined speed of the two vehicles
= 252 ÷
74 = 252 x
47 = 144 km/h
Average speed of the lorry : Average speed of the sports car = 4 : 5
4 u + 5 u = 9 u
9 u = 144
1 u = 144 ÷ 9 = 16
Average speed of the lorry
= 4 u
= 4 x 16
= 64 km/h
(b)
Time taken for the lorry and the sports car to meet travelling the rest of the journey
= 288 ÷ 144
= 2 h
Answer(s): (a) 64 km/h; (b) 2 h