The down stream speed of a boat is 50km/hr and its up stream speed is 10km/hr, then find the speed of boat in still water?  Choose the correct choice
A) 20km/hr
B) 30km/hr
C) 45km/hr
D) 50km/hr
E) 25km/hr
speed of boat in still water = 1/2 (50+10) = 30 km/hr   Answer is 30km/hr
<result>B</result>
The down stream speed of a boat is 50km/hr and its up stream speed is 10km/hr, then find the speed of boat in still water?