Question

A rectangular prism is completely packed with 90 cubes of edge length fraction 1 over 2 inch, without any gap or overlap. Which of the following describes the volume of this rectangular prism? 11 unit cubes and 1 smaller cube of volume fraction 1 over 8 cubic inch 22 unit cubes and 4 smaller cubes of volume fraction 1 over 8 cubic inch each 11 unit cubes and 2 smaller cubes of volume fraction 1 over 8 cubic inch each 22 unit cubes and 2 smaller cubes of volume fraction 1 over 8 cubic inch each Could someone teach me the steps please? I reviewed the lesson, I still don't understand

Answer 1

Check the picture below.

ok, notice the volume of the smaller cube forming the larger cube.  Keeping in mind that the larger cube has 90 of those small ones.

$\bf \stackrel{\textit{larger cube}}{V}=90\stackrel{\textit{small cube}}{V}\implies \stackrel{\textit{larger cube}}{V}=90\cdot \cfrac{1}{8}$