Two boys starts from the same place walking at the rate of 4 kmph and 5.5 kmph respectively in the same direction. What time will they take to be 10.5 km apart?  Choose one:
A) 8	B) 5	C) 7	D) 9	E) 6
Explanation:   Relative speed = 5.5 - 4= 
<gadget id="calculator">5.5 - 4</gadget>
<output>1.5</output>
1.5 kmph (because they walk in the same direction)   distance= 10.5 km   time = distance / speed=10.5/1.5= 
<gadget id="calculator">10.5/1.5</gadget>
<output>7</output>
7 hr   Answer :7
<result>C</result>
Two boys starts from the same place walking at the rate of 4 kmph and 5.5 kmph respectively in the same direction. What time will they take to be 10.5 km apart?