Texas Instruments PLUS TI-89 - Manual (Page 421)

404 Chapter 23: Activities
23ACTS.DOC TI-89/TI-92 Plus: Activities (English) Susan Gullord Revised: 02/23/01 1:24 PM Printed: 02/23/01 2:20 PM Page 404 of 26
Perform the following steps to find the interest rate ( i ) of an annuity
where the starting principal ( p ) is 1,000, number of compounding
periods ( n ) is 6, and the future value ( s ) is 2,000.
1. On the Home screen, enter the
equation to solve for p .
2. Enter the equation to solve
for n .
3. Enter the equation to solve for
i using the “with” operator.
solve(s=p ù (1+i)^n,i) | s=2000 and
p=1000 and n=6
Result: The interest rate is
12.246%.
Find the future value of an annuity using the values from the
previous example where the interest rate is 14%.
Enter the equation to solve for s .
solve(s=p ù (1+i)^n,s)| i=.14 and
p=1000 and n=6
Result: The future value at 14%
interest is 2,194.97.
Solving a Standard Annuity Problem
This activity can be used to find the interest rate, starting
principal, number of compounding periods, and future value of
an annuity.
Finding the Interest
Rate of an Annuity
Tip: To enter the “with” (|)
operator:
TI-89:
Í
TI-92 Plus: 2 È
Tip: Press ¥ ¸ to
obtain a floating-point result.
Finding the Future
Value of an Annuity