Chapter 6.2, Problem 4E

Reminder Round all answers to decimal places unless otherwise indicated.

The Spread of AIDS This table shows the cumulative number $N=N\left(t\right)$ of AIDS cases in the United States that have been reported to the Centers for Disease Control and Prevention by the end of the year given. (The source for these data, the U.S. Centers for Disease Control and Prevention in Atlanta, cautions that they are subject to retrospective change.)

a. What does $\frac{dN}{dt}$ mean in practical terms?

b. From $\text{2010}\text{to}\text{2014}$, was $\frac{dN}{dt}$ ever negative?

$t=year$	$N=totalcasereported$
$2010$	$1,140,203$
$2011$	$1,172,489$
$2012$	$1,191,061$
$2013$	$1,217,863$
$2014$	$1,236,994$