Riordan drove from Town Q to Town R which was 492 km away. He started from Town Q at an average speed of 78 km/h. He maintained this speed for 4 h before increasing it by 6 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 78
= 312 km
New speed for rest of the journey
= 78 + 6
= 84 km / h
Remaining distance for rest of the journey
= 492 - 312
= 180 km
Time taken for rest of the journey
= 180 ÷ 84
= 2 h
Total time taken
= 4 + 2
= 6 h
(b)
Average speed of the whole journey
= 492 ÷ 6
= 82 km
Answer(s): (a) 6 h; (b) 82km/h