City K and City L were 330 km apart. A sedan travelled from City K towards City L. At the same time, a lorry started from City L to City K. After travelling 1
12 h, the two vehicles were still 132 km apart. If the ratio of the average speed of the lorry to that of the sedan was 5 : 6, 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
= 330 - 132
= 198 km
Combined speed of the two vehicles
= 198 ÷
32 = 198 x
23 = 132 km/h
Average speed of the lorry : Average speed of the sedan = 5 : 6
5 u + 6 u = 11 u
11 u = 132
1 u = 132 ÷ 11 = 12
Average speed of the sedan
= 6 u
= 6 x 12
= 72 km/h
(b)
Time taken for the lorry and the sedan to meet travelling the rest of the journey
= 132 ÷ 132
= 1 h
Answer(s): (a) 72 km/h; (b) 1 h