City L and City M were 273 km apart. A sedan travelled from City L towards City M. At the same time, a lorry started from City M to City L. After travelling 1
13 h, the two vehicles were still 117 km apart. If the ratio of the average speed of the lorry to that of the sedan was 4 : 5, find
- the average speed of the sedan.
- 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
= 273 - 117
= 156 km
Combined speed of the two vehicles
= 156 ÷
43 = 156 x
34 = 117 km/h
Average speed of the lorry : Average speed of the sedan = 4 : 5
4 u + 5 u = 9 u
9 u = 117
1 u = 117 ÷ 9 = 13
Average speed of the sedan
= 5 u
= 5 x 13
= 65 km/h
(b)
Time taken for the lorry and the sedan to meet travelling the rest of the journey
= 117 ÷ 117
= 1 h
Answer(s): (a) 65 km/h; (b) 1 h