Speed in still water = (10 + 4)1/2 kmph = 7 kmph.
Calculate the speed of a boat in still water (in km/hr) if in one hour, the boat goes 10 km/hr downstream and 4 km/hr upstream.
Options:
1) 7 kmph
2) 8 kmph
3) 9 kmph
4) 7 kmph
5) 6 kmph