Walking (6/7) th of his usual speed, a man is 12 minutes too late. The usual time taken by him to cover that distance is:
New speed = (6/7)of usual speed.
New time = (7/6) of usual time.
Therefore (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.