How long does a train 250 meters long running at the rate of 72km/hr take to cross a bridge 150 meters in length?  Choose the correct choice from the following answers.
A) 10sec B) 20sec C) 25sec D) 30sec E) 35sec
Distance = length of train + length of bridge = 250+150= 
<gadget id="calculator">250+150</gadget>
<output>400</output>
400   speed= 72km/hr = 72*5/18= 
<gadget id="calculator">72*5/18</gadget>
<output>20</output>
20m/s   Required time= 400/20= 
<gadget id="calculator">400/20</gadget>
<output>20</output>
20 seconds   Answer is 20sec
<result>B</result>
How long does a train 250 meters long running at the rate of 72km/hr take to cross a bridge 150 meters in length?