The speed of the current is 5 km/hour. A motorboat goes 10 km upstream and back again to the starting point in 50 minutes. The speed (in km/hour) of the motorboat in still water is?

20 26 28 25

25

Let the speed of motorboat = U km/hr. ATQ,     \(\frac{10}{U + 5}\) + \(\frac{10}{U - 5}\) = 50 minutes Go through option or solve it U = 25 km/hr, will satisfy the equation.