A man rows at a speed of 5 km/h in still water. If the river current flows at 1 km/h, and it takes him 75 minutes to row to a destination and return, what is the distance to that destination?

Explanation

The downstream speed is 5 + 1 = 6 km/h, and the upstream speed is 5 - 1 = 4 km/h. Let the distance to the place be x km. The total time taken is the sum of downstream and upstream times: x/6 + x/4 = 75 minutes = 1.25 hours. Solving, (2x + 3x)/12 = 1.25, which gives 5x = 15, so x = 3 km. Therefore, the distance to the place is 3 kilometers.