Question

13)
A train is moving at a speed of 100 km/h. It takes 18 minutes to reach a station.
What should be its speed if the train wants to reach the station in 15 minutes.​

Answer 1

Answer:

The speed required is 120 kmph.

Step-by-step explanation:

Given :

Speed of the train = 100 km/h

Takes = 18 minutes

To find :

Speed of the train to reach the destination in 15 minutes

Solution :

Let the speed be m

$\begin{tabular}{|c|c|c|}\cline{1-3} Speed (x) & 100 kmph & m \\\cline{1-3}\ Time (y) & 18 minutes & 15 minutes \\\cline{1-3}\end{tabular}$

Inverse Variation -

$\boxed{\tt{x \times y = K}}$

$\tt{\implies} \: 100 \times 18 = m \times 15 \\ \\ \tt{\implies} \: 1800 = 15m \\ \\ \tt{\implies} \: m = \dfrac{1800}{15} \\ \\ \tt{\implies} \: m = 120$

The speed required is 120 kmph

$\therefore$ The speed required is 120 kmph.

Answer 2

Answer:

120 k m / hr

Step-by-step explanation:

Given :

Speed = 100 km / hr

Time = 18 min = 18 / 60 hr

We know :

Speed = Distance / Time

Distance = 100 × 18 / 60 = 10 × 3 km = 30 km

Now we have distance = 30 km

In second case time = 15 min = 15 / 60 hr = 1 / 4 hr

Again :

Speed = Distance / Time

Speed = 30 / 1 / 4 km / hr

Speed = 120 km / hr

Therefore ,  speed of the train should be 120 km / hr to reach the station in 15 minutes.​