Hello
One way to approach this is to introduce some random variables and consider CDFs. Let X be the original claim amount and let it follow the Pa(a,b) distribution.
Let Y =1.05X then:
P(Y <= y) = P(1.05X <= y) = P(X <= y/1.05)
= 1 - (b/(b+y/1.05))^a
= 1 - (1.05b/(1.05b+y))^a
Let b'=1.05b
FY(y) = 1 - (b'/(b'+y))^a
This is the CDF of the Pa(b', a) distribution.
Hope this helps!
Andy
Last edited: Apr 18, 2022