Kord is enlarging a picture to make a banner for the football team. He plans to repeatedly enlarge the picture 125% each time until it is the size he wants for his banner. The size of his picture can be modeled by the function [math]P(x) = 1.25^{x}[/math], where [math]x[/math] is the number of times the picture has been enlarged. Find the rate of change of the picture size between the first and third enlargement.
