Riordan drove from Town Q to Town R which was 480 km away. He started from Town Q at an average speed of 60 km/h. He maintained this speed for 4 h before increasing it by 4 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 60
= 240 km
New speed for rest of the journey
= 60 + 4
= 64 km / h
Remaining distance for rest of the journey
= 480 - 240
= 240 km
Time taken for rest of the journey
= 240 ÷ 64
= 2 h
Total time taken
= 4 + 2
= 6 h
(b)
Average speed of the whole journey
= 480 ÷ 6
= 80 km
Answer(s): (a) 6 h; (b) 80km/h