Chapter 5.4, Problem 16E

Reminder Round all answers to two decimal places unless otherwise indicated.

High School Graduates The following table shows the number, in millions, graduating from high school in the United States in the given year.

Year	Number
$1975$	$3.13$
$1980$	$3.04$
$1985$	$2.68$
$1990$	$2.57$
$1994$	$2.46$
$1999$	$2.76$
$2004$	$3.05$
$2009$	$3.32$

a. Make a plot of the data and explain why a linear model is not appropriate.

b. Use regression to find a linear model for the years $1975$ through $1990$. (In this part and the next. round regression line parameters to three decimal places.)

c. Use regression to find a linear model for the years $1994$ through $2009$.

d. Write a formula for a model of the number, in millions, graduating as a piecewise-defined function using the linear models from part b and part c.

e. Make a graph of the formula you found in part d.

f. The number graduating in $1995$ was $2.52\text{million}$. On the basis of your graph in part e, determine how this compares with what would be expected from your formula.