Final answer:
The scale factor used to reduce the size of the rug is 0.5.
Step-by-step explanation:
To find the scale factor used to reduce the size of the rug, we need to compare the areas of the two rugs. The area of Danielle's room rug is 32 sq. ft., and the area of the tree house rug is 8 sq. ft. The scale factor can be found by taking the square root of the ratio of the areas:
Scale factor = sqrt(8/32) = sqrt(1/4) = 1/2
Therefore, Danielle used a scale factor of 0.5 to reduce the size of the rug.