A and B walk around a circular track. A and B walk at a speed of 2 rounds per hour and 4 rounds per hour respectively. If they start at 7 a.m. from the same point in opposite directions, how many times shall they cross each other before 9.00 a.m.?	Choose the correct choice from the following choices:  A) 10  B) 6  C) 12  D) 8  E) 16
Relative speed = Speed of A + Speed of B (âˆ´ they walk in opposite directions)   = 2 + 4= 
<gadget id="calculator">2 + 4</gadget>
<output>6</output>
6 rounds per hour=&gt; They cross each other 6 times in 1 hour.   Time duration from 7.00 am to 9.00 am = 2 hour   Hence they cross each other 12 times before 9.00 am   Answer : 12
<result>C</result>
A and B walk around a circular track. A and B walk at a speed of 2 rounds per hour and 4 rounds per hour respectively. If they start at 7 a.m. from the same point in opposite directions, how many times shall they cross each other before 9.00 a.m.?