Step 1: Write out the formula for the volume of a cube
[tex]V_c=s^3[/tex][tex]\begin{gathered} \text{ Where} \\ V_c=\text{ the volume of the cube} \\ s-\text{ the length of one side of the cube} \end{gathered}[/tex]Step 2: Write out the given value of the side of the square and substitute it into the formula
[tex]s=\frac{1}{5}ft[/tex][tex]V_c=(\frac{1}{5})^3=\frac{1}{125}ft^3[/tex]Step 3: Write out the formula to find the number of cubes of a given volume that can fill the container of a given value
[tex]\text{ the number of cubes = }\frac{\text{ the volume of the container}}{\text{ the volume of the cube}}[/tex]Step 4: Write out the volume of the glass case and the cube and substitute them into the formula in step 3
[tex]\begin{gathered} \text{ the volume of the container = }\frac{4}{125}ft^3 \\ \text{ the volume of the cube = }\frac{1}{125}ft^3 \end{gathered}[/tex]Therefore,
[tex]\text{ the number of cubes = }\frac{\frac{4}{125}}{\frac{1}{125}}=\frac{4}{125}\times\frac{125}{1}=4[/tex]Hence, the number of cubes is 4
The right option is C