A rectangular prism 3cm by 5cm by 8cm is painted mauve and is then cut into 1 cm cubes what is the total unpainted surface area of these cubes

Guest Oct 29, 2020

#2**+2 **

A rectangular prism 3cm by 5cm by 8cm is painted mauve and is then cut into 1 cm cubes. what is the total unpainted surface area of these cubes ?

**Hello Guest!**

\(n=\frac{V}{1\cdot cm^3}=\frac{3\cdot 5\cdot 8\cdot cm^3}{1\cdot cm^3}=\color{blue}120\)

\(S_{unpainted}=n\cdot 6\cdot cm^2=120\cdot 6\cdot cm^2=\color{blue}720cm^2\)

\(S_{inside}=S_{unpainted}-S_{outside}=720cm^2-2\cdot (3\cdot 5+3\cdot 8+5\cdot 8)cm^2\)

\(S_{inside}=562cm^2\)

!

asinus Oct 29, 2020