Walking 78th of his usual speed, a man is 24 minutes late. What is the usual time taken by him to cover that distance?
2hr27 min
New speed = 7/8 of usual speed
Speed and time are inversely proportional.
Hence new time = 8/7 of usual time
Hence, 8/7 of usual time - usual time = 24 minutes
=> 1/7 of usual time = 24 minutes
=> Usual time = 24 × 7 = 168 minutes = 2 hours 48 minutes