15. 3.15 Eckelberger Products, Inc. makes high-speed recorders with highspeed scanning. The small company has been growing at an average rate of 75% per year for the past 4 years. The CEO asked you to convert the past growth rate into a monthly rate for its annual report. If the past growth rate was an effective rate, what was the effective growth rate per month? Solve by equation and spreadsheet function, if instructed to do so.