City V and City W were 455 km apart. A sedan travelled from City V towards City W. At the same time, a lorry started from City W to City V. After travelling 1
12 h, the two vehicles were still 182 km apart. If the ratio of the average speed of the lorry to that of the sedan was 6 : 7, 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
12 h by the two vehicles
= 455 - 182
= 273 km
Combined speed of the two vehicles
= 273 ÷
32 = 273 x
23 = 182 km/h
Average speed of the lorry : Average speed of the sedan = 6 : 7
6 u + 7 u = 13 u
13 u = 182
1 u = 182 ÷ 13 = 14
Average speed of the sedan
= 7 u
= 7 x 14
= 98 km/h
(b)
Time taken for the lorry and the sedan to meet travelling the rest of the journey
= 182 ÷ 182
= 1 h
Answer(s): (a) 98 km/h; (b) 1 h