Exercise 15 Let's assume you wish to make an investment of $10,000 and want to earn $500,000. The annual interest rate is 10%. You will make additional monthly contributions of $5,000. Using NPER formula calculate the number of monthly investments required to earn $500,000. Using What-if analysis in the Excel find out how number of months will vary at different combinations of rate and payments. Analyze the effect of annual interest rate change between 5%-15% and monthly payments between $1,000 and $10,000