A train speeds past a pole in 15 seconds and a platform 100 m long in 25 seconds. Its length is:  Choose the correct choice from the following:
A) 750 m  B) 300 m  C) 350 m  D) 150 m  E) 250 m
Let the length of the train be x metres and its speed by y m/sec.   Then, x/y = 15 =&gt; y =x/15   Therefore	x + 100/25 =	x/15   =&gt; 15(x + 100) = 25x   =&gt; 15x + 1500 = 25x   =&gt; 1500 = 10x   =&gt; x = 150 m.   Answer: 150 m
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A train speeds past a pole in 15 seconds and a platform 100 m long in 25 seconds. Its length is: