You are preparing a presentation to convince people that an ordinary annuity that earns 9% annual interest will have a higher future value than one that earns 5% annual interest. You decide that a graph will help convince people that this is true. a. Use excel to graph the future value versus time of an ordinary annuity with $250 payments per month at 5% and 9% annual interest. Make sure that your graph convinces people that 9% is better. b. Use the graph to estimate (or table) when the 9% annuity will have $1,000 more than the 5% annuity.