In a stream running at 3 Kmph, a motor boat goes 10 Km upstream and back again to the starting point in 57 minutes. Find the speed of motor boat in still water?	Choose the correct choice from the following.
A) 18 kmph	B) 22 kmph	C) 16 kmph	D) 20 kmph	E) None of these
Explanation:   Let the speed of motor boat instill water be X kmph   Then, speed in downstream = (X + 3) km   and. speed in upstream = (X - 3) kmph   Time taken to row 10km &amp; back = (10/X+3,10/X-3)   10/X+3 + 10/X-3 = 57/60   11X2 - 240X - 44 = 0   (X - 22)(11x + 2) = 0   X = 22 or X = -2/11   Then X = 22 kmph   Answer: Option 22 kmph
<result>B</result>
In a stream running at 3 Kmph, a motor boat goes 10 Km upstream and back again to the starting point in 57 minutes. Find the speed of motor boat in still water?