Intermediate Algebra – Student Workbook – Second Edition 2013

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Date: ________________
Mini-Lesson 3b
Writing Exponential Models and Doubling Time
In the previous lesson, we worked primarily with data and writing exponential equations from
data sets. We will do that again later in this lesson using EXPONENTIAL REGRESSION. First,
however, let’s see how to write exponential models given just some information about the
situation and no actual raw data. We will start with models of EXPONENTIAL GROWTH.
Problem 1 MEDIA EXAMPLE–WRITING EXPONENTIAL GROWTH
MODELS/DOUBLING TIME
In 2001, the population of a particular city was 22,395 with an identified growth rate of 6.2% per
year. Assume that this growth rate is fairly consistent from year to year.
a) Write the EXPONENTIAL GROWTH MODEL for this situation.
b) What is the approximate population of the city in 2006? Be sure and round to the nearest
person.
c) Estimate the number of years (to the nearest whole year) that it will take for the population to
double. In what actual year will this take place?
Scottsdale Community College Page 123 Intermediate Algebra