If a train runs with the speed of 72 km/h, it reaches its destination late by 15 minutes. However, if its speed is 90 km/h, it is late by only 5 minutes. The correct time to cover its journey in minutes is:

35

Distance = Speed × Time

Let the correct time to covers its journey be t min & Distance is same for both .

According to the question

 72 × \(\frac{t + 15 }{60}\) = 90 × \(\frac{t + 5 }{60}\)

 4 × (t + 15) = 5 × (t + 5)

 4t + 60 = 5t + 25

 (5t – 4t) = (60 – 25)

 t = 35 min

So , The correct time to covers its journey is 35 min