Question

A train travels 150km at a uniform speed. If the speed had been 9km/hr more, it
would have taken 1 hour less for the same journey. Find the speed of the train.​

Answer 1

Answer:

36km/h.

Step-by-step explanation:

Let the speed of train be x km /h

Distance = 180 km

So, time =  180 / x

When speed is 9 km/h more, time taken = 180 / x+9  

According to the given information:

180 / x  -  180 / x+9 = 1

180 (x+9-x) / x(x+9)  =  1

180 * 9 = x(x+9)

1620 = x2 + 9x  

x2 + 9x - 1620 = 0

x2 + 45x - 36x - 1620 = 0  

x(x+45) - 36(x+45) = 0

(x-36)(x+45) = 0

x = 36 or -45

But x being speed cannot be negative.

So, x = 36

Hence, the speed of the train is 36km/h.