Vincent drove from Town S to Town T which was 640 km away. He started from Town S at an average speed of 77 km/h. He maintained this speed for 3 h before increasing it by 9 km/h for the rest of the journey to Town T.
- How long did he take to complete the whole journey?
- What was his average speed from Town S to Town T?
(a)
Distance of 1st part of the journey
= 3 x 77
= 231 km
New speed for rest of the journey
= 77 + 9
= 86 km / h
Remaining distance for rest of the journey
= 640 - 231
= 409 km
Time taken for rest of the journey
= 409 ÷ 86
= 5 h
Total time taken
= 3 + 5
= 8 h
(b)
Average speed of the whole journey
= 640 ÷ 8
= 80 km
Answer(s): (a) 8 h; (b) 80km/h