Given data
The sliding distance is s = 3 m
The angle of inclination is 41 degree
The friction coefficient is 0.23
The free-body diagram of the above configuratin is shown below:
The expression for the force in the direction of motion is given as:

The expression for the velocity at the bottom is given as:
![\begin{gathered} v^2=2as \\ v=\sqrt[]{2as} \\ v=\sqrt[]{2*4.73m/s^{2^{}}*3\text{ m}} \\ v=5.327\text{ m/s} \end{gathered}](https://img.qammunity.org/2023/formulas/physics/college/q19bf3e107dguka29xtxvakuz6oekjzi4i.png)
Thus, the velocity of the boy at the bottom is 5.327 m/s.