Japheth drove from Town A to Town B which was 540 km away. He started from Town A at an average speed of 72 km/h. He maintained this speed for 4 h before increasing it by 5 km/h for the rest of the journey to Town B.
- How long did he take to complete the whole journey?
- What was his average speed from Town A to Town B?
(a)
Distance of 1st part of the journey
= 4 x 72
= 288 km
New speed for rest of the journey
= 72 + 5
= 77 km / h
Remaining distance for rest of the journey
= 540 - 288
= 252 km
Time taken for rest of the journey
= 252 ÷ 77
= 2 h
Total time taken
= 4 + 2
= 6 h
(b)
Average speed of the whole journey
= 540 ÷ 6
= 90 km
Answer(s): (a) 6 h; (b) 90km/h