Japheth drove from Town D to Town E which was 400 km away. He started from Town D at an average speed of 68 km/h. He maintained this speed for 2 h before increasing it by 5 km/h for the rest of the journey to Town E.
- How long did he take to complete the whole journey?
- What was his average speed from Town D to Town E?
(a)
Distance of 1st part of the journey
= 2 x 68
= 136 km
New speed for rest of the journey
= 68 + 5
= 73 km / h
Remaining distance for rest of the journey
= 400 - 136
= 264 km
Time taken for rest of the journey
= 264 ÷ 73
= 3 h
Total time taken
= 2 + 3
= 5 h
(b)
Average speed of the whole journey
= 400 ÷ 5
= 80 km
Answer(s): (a) 5 h; (b) 80km/h