What is the unit of work when force is measured in pounds and distance in feet?

A force of 50 newtons is applied to move an object 5 meters. What is the work done?

Calculate the work required to move an object from $x=0$ to $x=4$ meters if the force acting on it along the $x$-axis is $F\left(x\right)=4x^2$ newtons.

It takes a force of $24\text{ N}$ to stretch a spring $0.12\text{ m}$ from its natural length. What is the work required to stretch the spring from $0.12\text{ m}$ to $0.24\text{ m}$ beyond equilibrium?

An aquarium shaped like an inverted cone has a height of $8$ $\text{m}$ and a base radius of $2$ $\text{m}$. If the aquarium is full of water, how much work is required to pump all the water to the top of the aquarium and out? (Use $1000{\text{kg/m}}^3$ for water density and $g=9.8{\text{m/s}}^2$).