Billy drove from Town E to Town F which was 405 km away. He started from Town E at an average speed of 75 km/h. He maintained this speed for 4 h before increasing it by 4 km/h for the rest of the journey to Town F.
- How long did he take to complete the whole journey?
- What was his average speed from Town E to Town F?
(a)
Distance of 1st part of the journey
= 4 x 75
= 300 km
New speed for rest of the journey
= 75 + 4
= 79 km / h
Remaining distance for rest of the journey
= 405 - 300
= 105 km
Time taken for rest of the journey
= 105 ÷ 79
= 1 h
Total time taken
= 4 + 1
= 5 h
(b)
Average speed of the whole journey
= 405 ÷ 5
= 81 km
Answer(s): (a) 5 h; (b) 81km/h