A boy increases his speed to 9/5 times of his orignal speed. By doing this, he reaches his school 40 minutes before the usual time. How much time (in minutes) does he take usually?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. 90.
Let the normal time taken by him = T
as he increases his speed by 9/5 times the time taken decreases by 5/9 times
New time taken = 5T/9
⇒ T - 5T/9 = 4T/9
⇒ 4T/9 = 40 min
⇒ T = 90 mins
Thus,
The usual time taken by the boy to go to school is 90mins