$(3)$ points$]$

Use bisection to determine the drag coefficient needed so that an $8-kg$ parachutist has a velocity of $36\frac{m}{s}$ after $4s$ of free fall.

Note: The acceleration of gravity is $9\mathrm{.}81\frac{m}{s^2}.$ Start with initial guesses of $x_l=2$ and $x_u=6$ and iterate until the approximate relative error falls below $5\%.$ Also, perform an error check by substituting your final answer into the original equation.