Final answer:
The dimensions of the scaled rectangle are 12 inches by 20 inches, obtained by multiplying the original dimensions by the scale factor of 4. To scale the rectangle back to its original size, the correct scale factor is 1/4.
Step-by-step explanation:
When a rectangle with dimensions 3 inches by 5 inches is scaled by a factor of 4, we multiply both side lengths by 4 to find the dimensions of the scaled copy. Therefore, the new side lengths are:
3 inches × 4 = 12 inches (in length)
5 inches × 4 = 20 inches (in width).
To scale back the copy to its original size, you would use the inverse of the scale factor used to enlarge it. Since we multiplied by 4 to scale up, we divide by 4 to scale down, which is the same as multiplying by 1/4. Thus, the scale factor to return to the original size is 1/4.
The correct answer is: 12 inches by 20 inches; Scale factor of 1/4.