Glen drove from Town X to Town Y which was 640 km away. He started from Town X at an average speed of 70 km/h. He maintained this speed for 3 h before increasing it by 9 km/h for the rest of the journey to Town Y.
- How long did he take to complete the whole journey?
- What was his average speed from Town X to Town Y?
(a)
Distance of 1st part of the journey
= 3 x 70
= 210 km
New speed for rest of the journey
= 70 + 9
= 79 km / h
Remaining distance for rest of the journey
= 640 - 210
= 430 km
Time taken for rest of the journey
= 430 ÷ 79
= 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