Hello aspirant,

Let's the train's speed be x km/h.

Time taken =48/x.

If speed was increased by 10 km/h, time becomes 48/(x+10),which is 4 hours less.

So,

48/x - 48/(x+10)=4

Solving this gives x =6.

So the train's original speed is 6 km/h, and the faster speed would have been 16 km/h.

Hope the details will help you.

THANK YOU