Answer
$\approx 1.67 \times 10^{4} ft-lb$
Work Step by Step
The magnitude of gravitational force acting on the man +Can of paint $=160+25=185$ lbs
When we are moving in the upward direction, then we have
$F \cdot dr=185 dr$
and $W=\int_C F\cdot dr=185 \int_C dr$
Here, $C$ is a vertical line segment joining the lower and upper part of the silo, so we get
Work done, $W=\int_C F\cdot dr=(185) \int_C dr=185(90) \approx 1.67 \times 10^{4} ft-lb$
