Correct Answer - Option 3 : 30 min
GIVEN:
Ratio of speed = 4 ∶ 3 and time difference = 10 min
CONCEPT USED:
The ratio of speed is inverse of the Ratio of Time when the distance is constant
CALCULATION:
The ratio of Initial speed to Final speed = 4 ∶ 3
⇒ the Ratio of Initial Time to Final Time = 3 ∶ 4
⇒ The difference in time = 1
⇒ 1 = 10
⇒ Actual time taken = 3 × 10
⇒ 30 min
∴ The usual time taken to cover the journey is 30 min