Walking 6/7th of his usual speed, a man is 12 minutes too late. What is the usual time taken by him to cover that distance?
New speed =6/7 of usual speedSpeed and time are inversely proportional.Hence new time =7/6 of usual timeHence, 7/6 of usual time - usual time =12 minutes⇒1/6 of usual time =12 minutesTherefore, usual time =12×6=72 minutes=1 hour 12 minutes