walking 6/7 of his usual speed ,a man gets 12 minutes late . the usual time taken by him to cover a distance is:
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. -