A boat travels 72 km downstream in 8 hours and 84 km upstream in 12 hours. Find the speed of the boat in still water and the speed of the water current ? Options.
A) 6 and 1 kmph B) 8 and 2 kmph C) 8 and 1 kmph D) 9 and 1 kmph E) 2 and 1 kmph
Explanation:   Downstream speed = 72km/8hrs = 9 kmph   upstream speed 72  /8= 
<gadget id="calculator">72  /8</gadget>
<output>9</output>
9 kmph   upstream speed= 84km/12hrs = 7 kmph   speed of boat 84  /12= 
<gadget id="calculator">84  /12</gadget>
<output>7</output>
7 kmph   speed of boat= avg of downstream and upstream speeds   speed of boat = (9+7)/2= 
<gadget id="calculator">(9+7)/2</gadget>
<output>8</output>
8 kmph.   current speed= half of the difference of downstream and upstream speeds   currend speed = (9-7)/2= 
<gadget id="calculator">(9-7)/2</gadget>
<output>1</output>
1 kmph   Answer: 8 and 1 kmph
<result>C</result>
A boat travels 72 km downstream in 8 hours and 84 km upstream in 12 hours. Find the speed of the boat in still water and the speed of the water current ?