NTT Data Problems on Trains Quiz -1

The length of the train is equal to the distance covered by the train to cross the pole. So, we will find the distance traveled by train in 5 seconds by applying the following formula:

Distance= Speed x Time

Speed is given in Km/hr so we will convert it into m/s as answers are given in meters.

Speed= 72*5/18 = 20 m/s

Time = 5 seconds

Distance = 20* 5= 100 meters

If the train and boy are moving in the same direction then relative speed will be the difference between their individual speeds. In this problem, the other way to find the relative speed is to divide the distance covered (length of train) by the time taken by the train to cross the boy.

Relative Speed= 150/5 = 30

We will convert it into Km/hr

30*18/5 = 108 km/hr

Now, let the speed of the train be y km/hr. So, the relative speed, 108 km/hr = y km/hr - 5 km/hr

Y - 5 = 108

Y = 108 + 5

Y = 113 km/hr

The distance covered by the train when it crosses the bridge is equal to the sum of the length of the train and the length of the bridge.

Speed of train in m/s= 30 * 5/18 = 25/3

Time = 30 seconds

Let the length of the bridge is X.

\frac{Length \, of \, bridge + Length \, of \, train}{Time \:  taken\:   to\:   cross\:   the\:   bridge} = speed of train

( x + 144)/ 30 = speed of train

(X+144)/30 = 25/3

X + 144 = 250

X = 106

length of the bridge is 106 m

Speed of train in m/s = 180 x 5/18 = 50 m/s

Distance covered to cross the platform is equal to the sum of the length of the train and the length of the platform.

So, distance= 148+102 = 250 meters

Time = Distance / speed

= 250 /50

= 5 seconds

Time = Distance / Speed

In this problem, both the train and girl are moving so we will find the relative speed of the train. They are moving in the same direction, so the relative speed = (speed of train - speed of girl)

Relative Speed = (95 - 5) = 90 km/hr

Relative Speed in m/s = 90*5/18 = 25

Distance covered to cross the girl = length of the train (90 meters)

Time = Distance covered / Speed

Time= 90/ 25

= 3.6 sec

Time = Distance covered / speed

In this problem, both the train and girl are in motion so we will find the relative speed of the train. They are moving in the opposite direction, so the relative speed = (speed of train + speed of girl)

Relative Speed: (85+5) = 90 km/hr

Relative Speed in m/s= 90* 5/18 = 25

Distance covered to cross the girl = length of the train (200 meters)

Time = Distance covered / speed

= 225/25

= 9 Sec

Time = Distance covered / Speed

In this problem, both the trains are moving so we will find the relative speed of the train. They are moving in the opposite direction, so the relative speed will be sum of their individual speeds.

Relative speed: (42+48) = 90 km/hr

Relative speed in m/s = 90*5/18 = 25

Distance covered is equal to the sum of the length of trains: 147 + 153= 300 meters

Time =300/25

= 12 seconds

Time = Distance Covered / Speed

In this problem, both the trains are in motion so we will find the relative speed of the train. They are moving in the same direction, so the relative speed is equal to the difference of their individual speeds.

Relative Speed: (94-76) = 18 km/hr

Relative Speed in m/s: 18*5/18 = 5 m/s

Distance covered is equal to the sum of the length of trains: 133+152 = 285 meters

Time =285/5 = 57 seconds

Let the length of the train be L meter and speed be y m/sec

Therefore, time taken to cross the pole = L / y sec

and time taken to cross the platform = ( Length of train + Length of platform) / speed of train

Therefore L /y = 9

And, (L+185) / y = 19

⇒ 9 y + 185 = 19 y

∴ speed of train, y = 18.5 m/sec

And length of rain = L= 9 y = 166.5 m

 

Relative speed of the trains = 29 - 20 = 9 m/s

Time taken by the trains to cross each other

= Time taken to cover (133 + 137) m at 9 m/sec

= 270 /9

= 30 m/s