Find the speed of the man in still water? Statement I: A man can row 25 km upstream and 45 km downstream in 10 hours. Statement II: He can also travel 40 km upstream and 55 km downstream in 12 hours. Statement III: The distance travelled by man is same during upstream and downstream movement.

This is a boat and stream problem requiring still water speed. Statements I and II give us two equations: upstream and downstream distances with total times. Let boat speed in still water be b and stream speed be c. From I: 25/(b-c) + 45/(b+c) = 10. From II: 40/(b-c) + 55/(b+c) = 12. Two equations, two unknowns (b and c) - solvable. Statement III says upstream=downstream distance, which is not needed and doesn't help solve for b. So only I and II are required.