A train is moving at a speed of 132 km/hour. If the length of the train is 110 meters, how long will it take to cross a railway platform 165 meters long.

Answer: Option D

Explanation:

First convert speed into m/sec

Speed = 144*(5/18) = 40 m/sec

Time = Distance/speed
= 100/40 = 2.5 seconds

Answer: Option B

Explanation:

As we need to get answer in seconds, so never forget to convert speed into meter per second.

Speed = 30 km/hr = 30* 5/18 m/sec
= 25/3 m/sec

Distance = length of train = 100 meter

Required time =
$$\begin{aligned} \frac{Distance}{Speed} \\ = \frac{100}{\frac{25}{3}} \\ = 100* \frac{3}{25} = 12 sec \\ \end{aligned}$$

Answer: Option B

Explanation:

Speed = 72 km/hour = 72*(5/18) m/sec
= 20 m/sec

Total distance to be covered = 110+132 = 142 meters

Time = Distance/Speed
= 242/20 = 12.1 seconds

Answer: Option B

Explanation:

Relative Speed = 60+40 = 100 kmph
= 100*(5/18) = 250/9 m/sec

Distance = 140+160 = 300 meters

Time = Distance/Speed

$$\begin{aligned} 300*\frac{9}{250} = \frac{54}{5} \\ = 10.8 \text{ seconds} \end{aligned}$$

So the time trains will take to cross each other will be 10.8 seconds

Answer: Option D

Explanation:

Let the length of bridge is X [as always we do :)]
Speed of train is = 45*(5/18) m/sec = 25/2 m/sec
Time = 30 seconds

Total distance = 130+x
We know Speed = distance/time
so,
$$\begin{aligned} \frac{130+x}{30} = \frac{25}{2} \\ => 2(130+x) = 750 \\ x = 245 \text{ meters} \end{aligned}$$

So length of the bridge is 245 meters