Texas Instruments TI-82 User Manual - Page 199
Buying a Car, Now or Later?
UPC - 033317086337
View all Texas Instruments TI-82 manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 199 highlights
Buying a Car, Now or Later? You have identified the car you would like to buy, which costs 8,000. You can afford payments of 250 per month. You can either borrow the money at 10% annual interest (compounded monthly) and buy the car now, or invest the payments at 6% and pay cash for the car later. How long will it take to pay for the car each way? Procedure 1. Press z. Select the default MODE settings. Press y [STAT PLOT] and turn off all stat plots. 2. On the Home screen, store the values of the periodic interest rates. .06à12!Z .10à12!J 3. Press o. Turn off all functions and enter the formula to describe investing the money. Y2=250((1+Z)^X-1)àZ 4. Enter the formula to describe making car payments. Y3=8000-250(1-(1+J)^MX)àJ 5. To determine how many months will be required to pay cash, press y ãQUITä to return to the Home screen. Solve the equation (the amount saved less 8000) for X, using 36 months as the guess. (solve( is on the MATH MATH menu.) solve(Y2-8000,X,36) 6. To determine how long it will take to pay off the loan, enter: solve(Y3,X,36) 7. To calculate how much you would pay in total if you got a loan, press ¯ 250, which multiplies the months to pay off the loan (in Ans) by the payment amount. 8. Press y ãTABLEä to examine the amount saved versus the amount still owed for each time period. 9. Press p. Set the viewing WINDOW. Xmin = 0 Xmax = 47 Xscl = 12 Ymin = 0 Ymax = 8000 Yscl = 1000 10. Press r to examine the amounts graphically. Applications 14-5