Pierre drove from Town C to Town D which was 630 km away. He started from Town C at an average speed of 72 km/h. He maintained this speed for 2 h before increasing it by 6 km/h for the rest of the journey to Town D.
- How long did he take to complete the whole journey?
- What was his average speed from Town C to Town D?
(a)
Distance of 1st part of the journey
= 2 x 72
= 144 km
New speed for rest of the journey
= 72 + 6
= 78 km / h
Remaining distance for rest of the journey
= 630 - 144
= 486 km
Time taken for rest of the journey
= 486 ÷ 78
= 5 h
Total time taken
= 2 + 5
= 7 h
(b)
Average speed of the whole journey
= 630 ÷ 7
= 90 km
Answer(s): (a) 7 h; (b) 90km/h