The scale factor of the dilation can either be increased or decreased or enlarged or reduced but for the given parameters, the scale factor of the dilation is; 1.5
In dilation, the figure or image could be either enlarged or reduced. Now, we are told that OB' = 5cm and it was dilated to BB' which is 7.5 cm.
We can see that the length increased from 5 cm to 7.5cm. Thus, we can find the scale factor of dilation from;
Scale Factor = BB'/OB' = 7.5/5
Scale Factor = 1.5
Read more about scale factor at: https://brainly.com/question/10253650
