Final answer:
The scale factor for the size transformation from a rectangle with a width of 4 inches to a rectangle with a width of 8 inches is 2.
Step-by-step explanation:
In this case, the scale factor can be found by comparing the dimensions of the larger rectangle to the dimensions of the smaller rectangle. The width of the larger rectangle is 8 inches, while the width of the smaller rectangle is 4 inches.
The scale factor is the ratio of the larger width to the smaller width: 8 inches / 4 inches = 2.