City E and City F were 520 km apart. A sedan travelled from City E towards City F. At the same time, a lorry started from City F to City E. After travelling 1
23 h, the two vehicles were still 195 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 lorry.
- the time taken for them to meet travelling the rest of the journey. Express your answer in h.
(a)
Distance covered in 1
23 h by the two vehicles
= 520 - 195
= 325 km
Combined speed of the two vehicles
= 325 ÷
53 = 325 x
35 = 195 km/h
Average speed of the lorry : Average speed of the sedan = 6 : 7
6 u + 7 u = 13 u
13 u = 195
1 u = 195 ÷ 13 = 15
Average speed of the lorry
= 6 u
= 6 x 15
= 90 km/h
(b)
Time taken for the lorry and the sedan to meet travelling the rest of the journey
= 195 ÷ 195
= 1 h
Answer(s): (a) 90 km/h; (b) 1 h