Sam drove from Town D to Town E which was 680 km away. He started from Town D at an average speed of 72 km/h. He maintained this speed for 2 h before increasing it by 5 km/h for the rest of the journey to Town E.
- How long did he take to complete the whole journey?
- What was his average speed from Town D to Town E?
(a)
Distance of 1st part of the journey
= 2 x 72
= 144 km
New speed for rest of the journey
= 72 + 5
= 77 km / h
Remaining distance for rest of the journey
= 680 - 144
= 536 km
Time taken for rest of the journey
= 536 ÷ 77
= 6 h
Total time taken
= 2 + 6
= 8 h
(b)
Average speed of the whole journey
= 680 ÷ 8
= 85 km
Answer(s): (a) 8 h; (b) 85km/h