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?
Choose the correct choice from the following options.
A) 11  B) 12  C) 10.9  D) 14  E) 15
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 = 10.9 sec.   Answer: Option 10.9
<result>C</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?