The function for finding the population growth of people in a certain region is f(t) = 1000(2.2)t. what is the rate of increase?

For this case we have a function of the form:
 
 Where,
 A: initial amount
 b: growth rate
 t: time
 In this problem we have the following function:
 
 In this case, the growth rate is given by:
 
 
 the rate of increase is:
 b = 2.2

20000 as first it increases by 2500 then by 5000 so next it will increase by 10000