Walking 6/7th of his usual speed, a man is 12 minutes too late. The usual time taken by him to cover that distance is :
Select
A) 1 hr 20 min	B) 1 hr 10 min	C) 1 hr 11 min	D) 1 hr 12 min	E) None
Sol.   New speed = 6/7 of usual speed.   New time = 7/6 of usual time   ∴ [7/6 of usual time] - (usual time) = 1/5 hr.   ⇒ 1/6 of usual time = 1/5 hr ⇒ usual time = 6/5 hr = 1 hr 12 min.   Answer 1 hr 12 min
<result>D</result>
Walking 6/7th of his usual speed, a man is 12 minutes too late. The usual time taken by him to cover that distance is :