Xavier drove from Town Q to Town R which was 390 km away. He started from Town Q at an average speed of 70 km/h. He maintained this speed for 4 h before increasing it by 10 km/h for the rest of the journey to Town R.
- How long did he take to complete the whole journey?
- What was his average speed from Town Q to Town R?
(a)
Distance of 1st part of the journey
= 4 x 70
= 280 km
New speed for rest of the journey
= 70 + 10
= 80 km / h
Remaining distance for rest of the journey
= 390 - 280
= 110 km
Time taken for rest of the journey
= 110 ÷ 80
= 1 h
Total time taken
= 4 + 1
= 5 h
(b)
Average speed of the whole journey
= 390 ÷ 5
= 78 km
Answer(s): (a) 5 h; (b) 78km/h