David drove from Town W to Town X which was 328 km away. He started from Town W at an average speed of 70 km/h. He maintained this speed for 2 h before increasing it by 7 km/h for the rest of the journey to Town X.
- How long did he take to complete the whole journey?
- What was his average speed from Town W to Town X?
(a)
Distance of 1st part of the journey
= 2 x 70
= 140 km
New speed for rest of the journey
= 70 + 7
= 77 km / h
Remaining distance for rest of the journey
= 328 - 140
= 188 km
Time taken for rest of the journey
= 188 ÷ 77
= 2 h
Total time taken
= 2 + 2
= 4 h
(b)
Average speed of the whole journey
= 328 ÷ 4
= 82 km
Answer(s): (a) 4 h; (b) 82km/h