Answer:
95.36 ft
Step-by-step explanation:
Volume of a Cone[tex]=\frac{1}{3}\pi r^2 h[/tex]
Radius=7 ft, Height=12 ft
Therefore the volume of sand in the cone
[tex]=\frac{1}{3}\pi *7^2*12\\=615.7522$ ft^2[/tex]
If the sand was used to build as pyramid with a base of 4ft by 5ft.
Volume of a Pyramid[tex]=\frac{1}{3}*$Base Area* Height[/tex]
[tex]615.7522=\frac{1}{3}*(4*5)* Height\\615.7522=\dfrac{20}{3}* Height\\$Multiply both sides by \dfrac{3}{20}\\$Height =615.7522*\dfrac{3}{20}\\\\$Height of the pyramid=95.36 ft[/tex]