Chapter 5.5, Problem 8E

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

Vehicles parked The table shows the number, in thousands, of vehicles parked in the central business district of a certain city on a typical Friday as a function of the hour of the day.

Hour of the day	Vehicles parked (thousands)
$9$ A.M	$6.2$
$11$ A.M	$7.5$
$1$ P.M	$7.6$
$3$ P.M	$6.6$
$5$ P.M	$3.9$

a. Use regression to find a quadratic model for the data. (Round the regression parameters to three decimal places.)

b. Express using functional notation the number of vehicles parked on a typical Friday at $2$ P.M., and then estimate that value.

c. At what time of day is the number of vehicles parked at its greatest?