Zeph drove from Town U to Town V which was 648 km away. He started from Town U at an average speed of 70 km/h. He maintained this speed for 3 h before increasing it by 5 km/h for the rest of the journey to Town V.
- How long did he take to complete the whole journey?
- What was his average speed from Town U to Town V?
(a)
Distance of 1st part of the journey
= 3 x 70
= 210 km
New speed for rest of the journey
= 70 + 5
= 75 km / h
Remaining distance for rest of the journey
= 648 - 210
= 438 km
Time taken for rest of the journey
= 438 ÷ 75
= 5 h
Total time taken
= 3 + 5
= 8 h
(b)
Average speed of the whole journey
= 648 ÷ 8
= 81 km
Answer(s): (a) 8 h; (b) 81km/h