City C and City D were 396 km apart. A sedan travelled from City C towards City D. At the same time, a van started from City D to City C. After travelling 1
25 h, the two vehicles were still 165 km apart. If the ratio of the average speed of the van 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
25 h by the two vehicles
= 396 - 165
= 231 km
Combined speed of the two vehicles
= 231 ÷
75 = 231 x
57 = 165 km/h
Average speed of the van : Average speed of the sedan = 5 : 6
5 u + 6 u = 11 u
11 u = 165
1 u = 165 ÷ 11 = 15
Average speed of the sedan
= 6 u
= 6 x 15
= 90 km/h
(b)
Time taken for the van and the sedan to meet travelling the rest of the journey
= 165 ÷ 165
= 1 h
Answer(s): (a) 90 km/h; (b) 1 h