The distance between City C and City D was 640 km apart. A lorry travelled at an average speed of 81 km/h from City C to City D. At the same time, a convertible travelled at an average speed of 79 km/h from City D to City C. How much further did the lorry travel than the convertible when the lorry met the convertible on the way?
Combined speed of the lorry and the convertible
= 81 + 79
= 160 km/h
Time taken for the lorry and the convertible to meet
= 640 ÷ 160
= 4 h
Difference in the speed between the lorry and the convertible
= 81 - 79
= 2 km/h
Distance that the lorry travelled further than the convertible
= 4 x 2
= 8 km
Answer(s): 8 km