A person takes 40 minutes more than his usual time when he covers a distance of 20 km at 5 km/h. If he covers the same distance at 10 km/h, he takes x minutes less than the usual time. What is the value of x?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. 80.
Let usual speed = s
Then 4 − 20/s = 40 min = 2/3 hr
⇒ 20/s = 10/3 → s = 6 km/h
Usual time = 20/6 = 10/3 hr
At 10 km/h: time = 2 hr
x = (10/3 − 2) hr = 4/3 hr = 80 min