Chapter 4.4, Problem 6E

Special Rounding Instructions For this exercise set, round all regression parameters to three decimal places, but round all other answers to two decimal places unless otherwise indicated.

Cost of Scientific periodicals The table below shows the average cost $C$, in dollars, of chemistry and physics periodicals $t\text{years}$ after $1980$. ${}^{29}$

$t=\text{years}\text{since}1980$	$C=\text{cost,}\text{in}\text{dollars}$
$0$	$140$
$5$	$250$
$10$	$410$
$15$	$780$
$20$	$1300$
$22$	$1520$

a. Make an exponential model of $C$ as a function of $t$.

b. Plot the data and the exponential model.

c. What was the yearly percentage growth rate of the cost of chemistry and physics periodicals?

d. If this exponential trend continues, what will be the expected average cost of physics and chemistry periodicals in $2020$? Round your answer to the nearest dollar.