Dylan drove from Town X to Town Y which was 486 km away. He started from Town X at an average speed of 79 km/h. He maintained this speed for 3 h before increasing it by 4 km/h for the rest of the journey to Town Y.
- How long did he take to complete the whole journey?
- What was his average speed from Town X to Town Y?
(a)
Distance of 1st part of the journey
= 3 x 79
= 237 km
New speed for rest of the journey
= 79 + 4
= 83 km / h
Remaining distance for rest of the journey
= 486 - 237
= 249 km
Time taken for rest of the journey
= 249 ÷ 83
= 3 h
Total time taken
= 3 + 3
= 6 h
(b)
Average speed of the whole journey
= 486 ÷ 6
= 81 km
Answer(s): (a) 6 h; (b) 81km/h