If Raman reduces his usual speed by 30 percent, he will reach 15 minutes late. What is the usual time taken by him?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 35 minutes.
Speed = Distance/time
Speed is inversely proportional to time
Let his initial speed = 100x
His new speed = (100 - 30)% of 100x = 70x
Ratio of the speed = 10x : 7x
Ratio of time = 7x : 10x
Difference in time 10x - 7x = 15 minutes
⇒ 3x = 15 minutes
⇒ x = 5 minutes
So, his usual time = 7x = 7 × 5 = 35 minutes