Bobby drove from Town M to Town N which was 630 km away. He started from Town M at an average speed of 80 km/h. He maintained this speed for 3 h before increasing it by 9 km/h for the rest of the journey to Town N.
- How long did he take to complete the whole journey?
- What was his average speed from Town M to Town N?
(a)
Distance of 1st part of the journey
= 3 x 80
= 240 km
New speed for rest of the journey
= 80 + 9
= 89 km / h
Remaining distance for rest of the journey
= 630 - 240
= 390 km
Time taken for rest of the journey
= 390 ÷ 89
= 4 h
Total time taken
= 3 + 4
= 7 h
(b)
Average speed of the whole journey
= 630 ÷ 7
= 90 km
Answer(s): (a) 7 h; (b) 90km/h