In a stream running at 2 Kmph, a motor boat goes 10 Km upstream and back again to the starting point in 55 minutes. Find the speed of motor boat in still water?
Pick one: A) 11 B) 15 C) 22 D) 18 E) 25
Let the speed of motor boat instill water be X kmph   Then, speed in downstream = (X + 2) km   and. speed in upstream = (X - 2) kmph   Time taken to row 10km &amp; back = (10/X+2,10/X-2)   10/X+2 + 10/X-2 = 55/60   11X2 - 240X - 44 = 0   (X - 22)(11x + 2) = 0   X = 22 or X = -2/11   Then X = 22 kmph   Answer is 22.
<result>C</result>
In a stream running at 2 Kmph, a motor boat goes 10 Km upstream and back again to the starting point in 55 minutes. Find the speed of motor boat in still water?