1.  A man's speed with the current is 15 km/hr and the speed of the current is 2.5 km/hr. The man's speed against the current is :

A. 8.5 km/hr
B. 9 km/hr
C. 10 km/hr
D. 12.5 km/hr

Answer: Option C

Explanation:

Man's rate in still water = (15 - 2.5) km/hr = 12.5 km/hr.

Man's rate against the current = (12.5 - 2.5) km/hr = 10 km/hr.