Chapter 4.4, Problem 26E

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.

Medicare Expenditures The following table is from the Centers for Medicare & Medicaid Services. It shows Medicare expenditures $M$, in billions of dollars, $t$ years since 1990.

$t$ = time, in years since 1990	$M$= disbursements, in billions
$0$	$109.7$
$5$	$180.1$
$10$	$219.3$
$15$	$336.9$
$20$	$521.2$
$25$	$635.3$

a. Make an exponential model of $M$ versus $t$.

b. Plot the data and the exponential model.

c. When does the exponential model indicate that disbursements will reach one trillion dollars(that is, $M=1000$)?