Compound Int

This program uses the compound interest formula  which gives the amount in an account for a principal of P, invested for t years at an interest rate of r (decimal) p.a. and calculated n times per year.  It will find any of the values in the formula, given the values of all the others.

Int Comparison
 This program will produce a table comparing the growth of an investment for a given annual interest rate under compound and simple interest. Interest rate is entered as a decimal  (eg. 25% should be entered as 0.25) When the program terminates you can press NUM to see the table or PLOT to see a graph. The axes are automatically set up by the program. Note: Sequences U1 and U2 in the Sequence aplet are overwritten by this program and the Sequence aplet becomes the active one.

Loan Table
 This program will calculate the length of a loan, displaying the result in the NUM view and automatically setting up the PLOT view to show the result. Payments can be made annually, quarterly or monthly. eg. I borrow \$10,000 at 7.5% p.a. interest, compounded quarterly and repay it at a rate of \$200 per quarter, beginning on Jan 1, 1990. As can be seen in the NUM view right, the equations are set up to go to zero at the completion of the loan, rather than continuing into negative numbers. The time is shown in column U1, with 1990.03 corresponding (for example) to the 3rd quarter of 1990.  In the case of this loan, it is repaid during the 2nd quarter of 2027.  The exact length is also given, in this case as 37 years and 3 months. It should be noted that the final payment will be very slightly incorrect due to the fact that interest is calculated for the entire quarter instead of being done 'pro-rata' as the bank would. Note: Sequences U1 and U2 in the Sequence aplet are overwritten by this program and the Sequence aplet becomes the active one.

Simple Intrst
 This program will use the I=PRT formula for simple interest to find the principle, the amount of interest paid, the interest rate, the time, the total paid, or the weekly, monthly or quaterly repayment amount. The user must supply all values except the one being solved for.