AFCAT Model Paper 8

Given: The average speed of train = 40 km/hr If the average speed is 35 km/hr then it is delayed by 15 minutes. Formula Used: Time = Distance/Speed Calculation: Let the distance of total journey be ‘d’ km. Case 1st : Given, with an average speed of 40 km/hr, a train reaches its destination in time. Speed = 40 km/hr, Time = d/40 hr This is the time actually required for the journey. Case 2nd : Given, with an average speed of 35 km/hr, it is late by 15 minutes. Speed = 35 km/hr, Time $= \frac{d}{35}$ As he is late by 15 minutes, the actual time for journey $= \left(\frac{d}{35} - \frac{15}{60}\right)\text{hr}$ Actual time of journey should be same. ⇒ $\frac{d}{40} = \frac{d}{35} - \frac{1}{4}$ $\Rightarrow \frac{1}{4} = \frac{d}{35} - \frac{d}{40}$ $\Rightarrow \frac{1}{4} = \frac{d}{280}$ ⇒ d = 70 km ∴ The required distance is 70 km.