A train moves fast a telegraph post and a bridge 240 m long in 8 sec and 20 sec respectively. What is the speed of the train? Pick:	A) 75	B) 39	C) 79	D) 72	E) 71
Let the length of the train be x m and its speed be y m/sec.   Then, x/y = 8 =&gt; x = 8y   (x + 240)/20 = y   y = 20   Speed = 20 m/sec = 20 * 18/5= 
<gadget id="calculator">20 * 18/5</gadget>
<output>72</output>
72 km/hr.   Answer:72
<result>D</result>
A train moves fast a telegraph post and a bridge 240 m long in 8 sec and 20 sec respectively. What is the speed of the train?