Justin drove from Town Q to Town R which was 420 km away. He started from Town Q at an average speed of 69 km/h. He maintained this speed for 4 h before increasing it by 5 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 69
= 276 km
New speed for rest of the journey
= 69 + 5
= 74 km / h
Remaining distance for rest of the journey
= 420 - 276
= 144 km
Time taken for rest of the journey
= 144 ÷ 74
= 2 h
Total time taken
= 4 + 2
= 6 h
(b)
Average speed of the whole journey
= 420 ÷ 6
= 70 km
Answer(s): (a) 6 h; (b) 70km/h