Billy drove from Town K to Town L which was 380 km away. He started from Town K at an average speed of 70 km/h. He maintained this speed for 4 h before increasing it by 8 km/h for the rest of the journey to Town L.
- How long did he take to complete the whole journey?
- What was his average speed from Town K to Town L?
(a)
Distance of 1st part of the journey
= 4 x 70
= 280 km
New speed for rest of the journey
= 70 + 8
= 78 km / h
Remaining distance for rest of the journey
= 380 - 280
= 100 km
Time taken for rest of the journey
= 100 ÷ 78
= 1 h
Total time taken
= 4 + 1
= 5 h
(b)
Average speed of the whole journey
= 380 ÷ 5
= 76 km
Answer(s): (a) 5 h; (b) 76km/h