A man decided to cover a distance of 6 km in 84 minutes. He decided to cover two thirds of the distance at 4 kmph and the remaining at some different speed. Find the speed after the two third distance has been covered.

Question: A man decided to cover a distance of 6 km in 84 minutes. He decided to cover two thirds of the distance at 4 kmph and the remaining at some different speed. Find the speed after the two third distance has been covered.

Solution:
We are given that two thirds of the 6 km was covered at 4 kmph
∴ 4 km distance was covered at 4 kmph.
Time taken to cover 4 km = (4 km)/(4 kmph) = 1 hr = 60 minutes

Time left = 84 - 60 = 24 minutes

Now,
The man has to cover remaining 2 km in 24 minutes = 24/60 hours = 0.4 hours

Speed required for remaining 2 km = 2/ 0.4 = 5 kmph