Valen drove from Town K to Town L which was 400 km away. He started from Town K at an average speed of 78 km/h. He maintained this speed for 3 h before increasing it by 7 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
= 3 x 78
= 234 km
New speed for rest of the journey
= 78 + 7
= 85 km / h
Remaining distance for rest of the journey
= 400 - 234
= 166 km
Time taken for rest of the journey
= 166 ÷ 85
= 2 h
Total time taken
= 3 + 2
= 5 h
(b)
Average speed of the whole journey
= 400 ÷ 5
= 80 km
Answer(s): (a) 5 h; (b) 80km/h