Justin drove from Town L to Town M which was 595 km away. He started from Town L at an average speed of 68 km/h. He maintained this speed for 4 h before increasing it by 4 km/h for the rest of the journey to Town M.
- How long did he take to complete the whole journey?
- What was his average speed from Town L to Town M?
(a)
Distance of 1st part of the journey
= 4 x 68
= 272 km
New speed for rest of the journey
= 68 + 4
= 72 km / h
Remaining distance for rest of the journey
= 595 - 272
= 323 km
Time taken for rest of the journey
= 323 ÷ 72
= 3 h
Total time taken
= 4 + 3
= 7 h
(b)
Average speed of the whole journey
= 595 ÷ 7
= 85 km
Answer(s): (a) 7 h; (b) 85km/h