In a stream running at 2kmph,a motor boat goes 6km upstream and back again to the starting point in 33 minutes.find the speed of the motorboat in still water.  Choices:
A) 22	B) 24	C) 26	D) 28	E) none of them

Rationale: let the speed of the motarboat in still water be x kmph . then , 6 / x + 2 + 6 / x - 2 = 33 / 60 11 x 2 - 240 x - 44 = 0 11 x 2 - 242 x + 2 x - 44 = 0 ( x - 22 ) ( 11 x + 2 ) = 0 x = 22 . answer is a
Answer: A