City L and City M were 936 km apart. A car travelled from City L towards City M. At the same time, a bus started from City M to City L. After travelling 1¹₂ h, the two vehicles were still 624 km apart. If the ratio of the average speed of the bus to that of the car was 6 : 7, find

1. the average speed of the bus.
2. the time taken for them to meet travelling the rest of the journey. Express your answer in h.

(a)
Distance covered in 1¹₂ h by the two vehicles
= 936 - 624
= 312 km

Combined speed of the two vehicles
= 312 ÷ ³₂
= 312 x ²₃
= 208 km/h

Average speed of the bus : Average speed of the car = 6 : 7

6 u + 7 u = 13 u 
13 u = 208

1 u = 208 ÷ 13 = 16

Average speed of the bus
= 6 u
= 6 x 16
= 96 km/h

(b)
Time taken for the bus and the car to meet travelling the rest of the journey
= 624 ÷ 208
= 3 h 

Answer(s): (a) 96 km/h; (b) 3 h