A 300 m long train crosses a platform in 39 sec while it crosses a signal pole in 10 sec. What is the length of the platform? Pick one:  A) 187 m  B) 350 m  C) 267 m  D) 287 m  E) 870 m
Speed = 300/10= 
<gadget id="calculator">300/10</gadget>
<output>30</output>
30 m/sec.   Let the length of the platform be x meters.   Then, (x + 300)/39=30   =&gt; x = 870m.   Answer:870 m
<result>E</result>
A 300 m long train crosses a platform in 39 sec while it crosses a signal pole in 10 sec. What is the length of the platform?