Justin drove from Town H to Town J which was 539 km away. He started from Town H at an average speed of 60 km/h. He maintained this speed for 4 h before increasing it by 5 km/h for the rest of the journey to Town J.
- How long did he take to complete the whole journey?
- What was his average speed from Town H to Town J?
(a)
Distance of 1st part of the journey
= 4 x 60
= 240 km
New speed for rest of the journey
= 60 + 5
= 65 km / h
Remaining distance for rest of the journey
= 539 - 240
= 299 km
Time taken for rest of the journey
= 299 ÷ 65
= 3 h
Total time taken
= 4 + 3
= 7 h
(b)
Average speed of the whole journey
= 539 ÷ 7
= 77 km
Answer(s): (a) 7 h; (b) 77km/h