Having The Calculator Enter Evenly Spaced Input Values; Finding Percentage Differences; Finding An Exponential Function To Model Data - Texas Instruments TI-84 Plus Manual

HAVING THE CALCULATOR ENTER EVENLY SPACED INPUT VALUES When an
input list consists of many values that are the same distance apart, there is a calculator
command that will generate the list so that you do not have to type the values in one by one.
The syntax for this sequence command is seq(formula, variable, first value, last value,
increment). When entering years that differ by 1, the formula is the same as the variable and
the increment is 1. Any letter can be used for the variable -- we choose to use
illustrate the sequence command use to enter the input for the population data in Table 1.17 in
Section 1.3 of Calculus Concepts.
Year of mandate
Population
Clear any old data from lists
position the cursor in the first list so that
Generate the list of the years of the mandate beginning with 0,
ending with 6, and differing by 1 with
► OPS 5 [seq X,T,θ,n , X,T,θ,n , 0 , 6 , 1 ) .
Press
ENTER
must manually enter the output values in
FINDING PERCENTAGE DIFFERENCES When the input values are evenly spaced, use
1.3.1
program to compute the percentage differences in the output data. If the data are
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perfectly exponential (that is, every data point falls on the exponential function), the percent-
age change (which in this case would equal the percentage differences) in the output is
constant. If the percentage differences are close to constant, this is an indication that an
exponential model may be appropriate.
Return to the home screen. Find the percentage differences in the population data with pro-
gram . Press
DIFF
Press
ENTER
right appears on your screen. Press
STAT 1 [EDIT]
view the percentage differences in list
L5.
The percentage differences in list L5 are close to constant, so an exponential function will
probably give a good fit to these data.
FINDING AN EXPONENTIAL FUNCTION TO MODEL DATA Use your calculator to
find an exponential equation to model the small town population data. The exponential
function we use is of the form y = ab
as years) whenever you find an exponential model. If you don't align to smaller values, the
calculator may return an error message or an incorrect function due to computation errors.
28
0 1 2
7290 5978 4902
and . To enter the input data,
L1 L2
and the sequence of years is pasted into
and then the number that is to the left of the
PRGM
and the message on the
and to
► ► ►
. It is very important that you align large numbers (such
x
3 4 5
4020 3296 2703
is darkened.
L1
2ND STAT (LIST)
You
L1.
L2.
Copyright © Houghton Mifflin Company. All rights reserved.
Chapter 1
. We
X
6
2216
program location.
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