Albert drove from Town M to Town N which was 546 km away. He started from Town M at an average speed of 75 km/h. He maintained this speed for 3 h before increasing it by 4 km/h for the rest of the journey to Town N.
- How long did he take to complete the whole journey?
- What was his average speed from Town M to Town N?
(a)
Distance of 1st part of the journey
= 3 x 75
= 225 km
New speed for rest of the journey
= 75 + 4
= 79 km / h
Remaining distance for rest of the journey
= 546 - 225
= 321 km
Time taken for rest of the journey
= 321 ÷ 79
= 4 h
Total time taken
= 3 + 4
= 7 h
(b)
Average speed of the whole journey
= 546 ÷ 7
= 78 km
Answer(s): (a) 7 h; (b) 78km/h