We must recall that to a rectangular prism has a volume of V = L(W)(H).
Since Chloe has 20 unit cubes, this means she can as many prisms as long as they satisfy 20 = L(W)(H).
Listing down the prime factors of 20, we have 20 = 1 x 2 x 2 x 5. We can group them into three and list down the possible combinations as shown below.
1 x 4 x 5 = 20 | 1 x 2 x 10 =20 | 2 x 2 x 5 = 20 | 1 x 1 x 20 = 20
The rest are just rearrangement of the four above. That means Chloe can build 4 different types of prism.
The following choices for this question were retrived from another source.
Then, the answer would be A: 4.
