A train moves fast a telegraph post and a bridge 260 m long in 8 sec and 20 sec respectively. What is the speed of the train? Choose the correct option
A) 79.5 B) 39.5 C) 79.9 D) 78.0 E) 79.0
Let the length of the train be x m and its speed be y m/sec.   Then, x/y = 8 =&gt; x = 8y   (x + 260)/20 = y   y = 21.67   Speed = 21.67m/sec = 21.67 * 18/5 = 78 km/hr.   Answer:78.0
<result>D</result>
A train moves fast a telegraph post and a bridge 260 m long in 8 sec and 20 sec respectively. What is the speed of the train?