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
- 18 kmph
- 22 kmph
- 16 kmph
- 20 kmph
- Explanation:
speed in downstream = (X + 2) km
speed in upstream = (X - 2) kmph
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