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?

Question

Q:

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?

Answer 1

New speed =6/7 of usual speed
Speed and time are inversely proportional.
Hence new time =7/6 of usual time
Hence, 7/6 of usual time - usual time =12 minutes
⇒1/6 of usual time =12 minutes
Therefore, usual time =12×6=72 minutes=1 hour 12 minutes