25. What is the scale factor if a 6 inch by 6 inch photograph is enlarged to a poster that is $4 \mathrm{ft}$. by $4 \mathrm{ft}$.? $4 \mathrm{ft}=48 \mathrm{in}$

Step 1 ：Convert the length from feet to inches: $4 \mathrm{ft}=48 \mathrm{in}$

Step 2 ：The scale factor is the ratio of the lengths of the corresponding sides of the two similar figures. In this case, the two figures are the original photograph and the enlarged poster. The length of the side of the poster is 48 inches and the length of the side of the photograph is 6 inches. So, the scale factor is 48/6.

Step 3 ：Calculate the scale factor: \(\frac{48}{6} = 8.0\)

Step 4 ：Final Answer: The scale factor is \(\boxed{8}\)