City X and City Y were 748 km apart. A car travelled from City X towards City Y. At the same time, a lorry started from City Y to City X. After travelling 1
14 h, the two vehicles were still 528 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
14 h by the two vehicles
= 748 - 528
= 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 car = 5 : 6
5 u + 6 u = 11 u
11 u = 176
1 u = 176 ÷ 11 = 16
Average speed of the lorry
= 5 u
= 5 x 16
= 80 km/h
(b)
Time taken for the lorry and the car to meet travelling the rest of the journey
= 528 ÷ 176
= 3 h
Answer(s): (a) 80 km/h; (b) 3 h