For Exercises 22-24, refer to the following. The formula for the average growth rate over a period of time is even simpler than the one for the exponential reserve of a resource. If usage at the beginning is and at the end of an interval of years it is , then the average annual rate of growth is
22. The U.S. population was 63 million in 1890 and 321 million in 2015 (at roughly the same times of the year). What was the average annual rate of growth, to two decimal places?