The gravitational potential is given by:
[tex]U=mgh[/tex]where m is the mass, g is the acceleration of gravity and h is the height.
In this case we know the potential is 4942 J, the height is 6.15 m and the gravitational acceleration is 9.8 m/s^2; plugging this values in the equation above and solving for the mass we have:
[tex]\begin{gathered} 4942=(9.8)(6.15)m \\ m=\frac{4942}{(9.8)(6.15)} \\ m=82 \end{gathered}[/tex]Therefore, the mass of the faulter is 82 kg