$+400pts\frac{}{1200}$

Question $5$ of $12$

A large, rectangular container is floating in the ocean with $\frac{1}{4}$ of its total volume submerged beneath the surface. The container has a mass $m$ and a total volume $V.$ In terms of given variables, what mass of sand would have to be poured inside the container so that it floated with $\frac{3}{4}$ of its total volume submerged instead? Assume this can be accomplished with a quantity of sand that fits entirely inside the container.