A rower can row upstream at 7 km/hr and downstream at 13 km/hr. What is the rower's rate in still water? Choose the correct choice from the following choices:
A) 8 km/hr
B) 9 km/hr
C) 10 km/hr
D) 11 km/hr
E) 12 km/hr
The rate in still water is 1/2 * (13 + 7)= 
<gadget id="calculator">1/2 * (13 + 7)</gadget>
<output>10</output>
10 km/hr   The answer is 10 km/hr.
<result>C</result>
A rower can row upstream at 7 km/hr and downstream at 13 km/hr. What is the rower's rate in still water?