The population of a certain country grew from 2.1 million in 1970 to 3 million in 1995.

a) What was the average rate of change of the population over that period? (worked out to be 36 thousand people per year).

b)Suppose that the population grew exponentially. By what percentage did the population grow each year? What was the average rate of change from 1970 to 1975? What was the average rate of change from 1990 to 1995? Illustrate your answers using a sketch.

I worked out no. a), but I am having problems with number b) could some please help? This question appeared under a section in my note under the heading of derivatives and linear approximations, so I am thinking you have to use that to solve the problem.