Lee drove from Town C to Town D which was 498 km away. He started from Town C at an average speed of 72 km/h. He maintained this speed for 2 h before increasing it by 9 km/h for the rest of the journey to Town D.
- How long did he take to complete the whole journey?
- What was his average speed from Town C to Town D?
(a)
Distance of 1st part of the journey
= 2 x 72
= 144 km
New speed for rest of the journey
= 72 + 9
= 81 km / h
Remaining distance for rest of the journey
= 498 - 144
= 354 km
Time taken for rest of the journey
= 354 ÷ 81
= 4 h
Total time taken
= 2 + 4
= 6 h
(b)
Average speed of the whole journey
= 498 ÷ 6
= 83 km
Answer(s): (a) 6 h; (b) 83km/h