Julian drove from Town B to Town C which was 420 km away. He started from Town B at an average speed of 63 km/h. He maintained this speed for 4 h before increasing it by 9 km/h for the rest of the journey to Town C.
- How long did he take to complete the whole journey?
- What was his average speed from Town B to Town C?
(a)
Distance of 1st part of the journey
= 4 x 63
= 252 km
New speed for rest of the journey
= 63 + 9
= 72 km / h
Remaining distance for rest of the journey
= 420 - 252
= 168 km
Time taken for rest of the journey
= 168 ÷ 72
= 1 h
Total time taken
= 4 + 1
= 5 h
(b)
Average speed of the whole journey
= 420 ÷ 5
= 84 km
Answer(s): (a) 5 h; (b) 84km/h