Scale factor is defined as a number which multiplies or scales some quantity.
The shape of the figure remains same, the image becomes larger or smaller.
If the scale factor is greater than one, then the image is enlarged.
If the scale factor is less than 1 but greater that 0, then the image becomes smaller.
In the above image, AD = 2 units.
It's corresponding side PS = 3 units
Similarly AB = 1 unit and PQ = 1.5 units
Hence , 1 * 1.5 = 1.5
2*1.5 = 3
Hence, the scale factor of the given image is 1.5 ... Answer