A man can row upstream at 5km/hr and down stream at 13km/hr find mans rate in still water ?  Choose the correct choice from the following answers
A) 7.5km/hr
B) 3.5km/hr
C) 9km/hr
D) 4km/hr
E) 5km/hr
given upstream(u) =5km/hr   down stream (v)= 13km/hr rate in still water =1/2(u+v)=1/2(5+13)=9km/hr Answer is (9km/hr)
<result>C</result>
A man can row upstream at 5km/hr and down stream at 13km/hr find mans rate in still water ?