How many seconds will a 400 meter long train take to cross a man walking with a speed of 3 km/hr in the direction of the moving train if the speed of the train is 63 km/hr?	Choose the correct choice from the following answers:  A) 287  B) 288  C) 900  D) 277  E) 121
Let length of tunnel is x meter   Distance = 400+x meter   Time = 1 minute = 60 seconds   Speed = 78 km/hr = 78*5/18 m/s = 65/3 m/s   Distance = Speed*Time   400+x = (65/3) * 60   400+x = 20 * 65= 
<gadget id="calculator">20 * 65</gadget>
<output>1_300</output>
1300   x= 1300 - 400= 
<gadget id="calculator">1300 - 400</gadget>
<output>900</output>
900 meters   Answer: 900
<result>C</result>
How many seconds will a 400 meter long train take to cross a man walking with a speed of 3 km/hr in the direction of the moving train if the speed of the train is 63 km/hr?