A person rows 0.75 km upstream in 11 minutes and covers the same distance downstream in 7 minutes. What is the rower's speed in still water in km/h?

Explanation

To find the speed in still water, first calculate the upstream and downstream speeds. Upstream speed = 0.75 km / (11/60) hr = 4.09 km/h. Downstream speed = 0.75 km / (7/60) hr = 6.43 km/h. The speed in still water is the average of these two speeds: (4.09 + 6.43) / 2 = 5.26 km/h, approximately 5 km/h.