Question

a train travels 180km at a uniform speed. if the speed had been 9 km/h more, it would have taken 1 hour less for the same journey. find the speed of the train.

Answer 1

Let the uniform speed of train be x km/hr.
Therefore time taken=180/x hr.
Now speed=x+9 km/hr.
Time taken =180/x+9 hr.
A/q
180/x-180/x+9 = 1
x=9 or x= -18
therefore the speed of train =9 km/hr

Answer 2

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.