Question

A train 800 metres long is running at a speed of 78 km/hr. If it crosses a tunnel in 1 minute, then the length of the tunnel (in meters) is: 130 360 500 540

Answer 1

Let length of tunnel is x meter

Distance = 800+x meter 

Time = 1 minute = 60 seconds

Speed = 78 km/hr = 78*5/18 m/s = 65/3 m/s

Distance = Speed*Time

\begin{aligned}

=> 800+x = \frac{65}{3}*60 \\

=> 800+x = 20*65 = 1300 \\

=> x = 1300 - 800 = 500 \\

\end{aligned}

So the length of the tunnel is 500 meters.

Answer 2

Explanation:

Let length of tunnel is x meter
Distance = 800+x meter 
Time = 1 minute = 60 seconds

Speed = 78 km/hr = 78*5/18 m/s = 65/3 m/s

Distance = Speed*Time

=>800+x=653∗60
=>800+x=20∗65=1300
=>x=1300−800=500

I have written it by myself please mark it as the brainllist if it will help you
please say thanks for this answer too