Two trains 500 m and 750 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time which they take to cross each other is?	Pick:
A) 10.6
B) 45
C) 10.4
D) 10.8
E) 10.1
Relative speed = 60 + 40= 
<gadget id="calculator">60 + 40</gadget>
<output>100</output>
100 km/hr.= 100 * 5/18 = 250/9 m/sec.   Distance covered in crossing each other = 500 + 750= 
<gadget id="calculator">500 + 750</gadget>
<output>1_250</output>
1250 m.   Required time= 1250 * 9/250= 
<gadget id="calculator">1250 * 9/250</gadget>
<output>45</output>
45 sec.   Answer: 45
<result>B</result>
Two trains 500 m and 750 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time which they take to cross each other is?