Correct Answer - Option 2 : 50 minutes
Calculation:
Let the man’s usual speed be x km/hr and the distance to be covered = y km.
His usual time is (y/x) hours.
When his speed is 5/3 his usual speed the time taken is (3y/5x) hours
Now, (y/x) + 20/60 = (3x/5y)
⇒ (y/x − 3y/5x) = 20/60
⇒ (5y − 3y)/5x = 1/3
⇒ 2y/5x = 1/3
⇒ y/x = 5/6 [Hence 5/6 hour change in minutes - (5/6) × 60]
His usual time is 50 minutes.
