Two trains of equal lengths take 10 sec and 12 sec respectively to cross a telegraph post. If the length of each train be 120 m, in what time will they cross other travelling in opposite direction? Select: A) 22 B) 12 C) 77 D) 99 E) 11
Speed of the first train = 120/10= 
<gadget id="calculator">120/10</gadget>
<output>12</output>
12 m/sec.   Speed of the second train= 120/12= 
<gadget id="calculator">120/12</gadget>
<output>10</output>
10 m/sec.   Relative speed= 12 + 10= 
<gadget id="calculator">12 + 10</gadget>
<output>22</output>
22 m/sec.   Required time= (120 + 120)/22 = 11 sec.   Answer: 11
<result>E</result>
Two trains of equal lengths take 10 sec and 12 sec respectively to cross a telegraph post. If the length of each train be 120 m, in what time will they cross other travelling in opposite direction?