Answer
$B=1000\cdot(1.5)^{t/2}$
$16,800,000$ bacteria
Work Step by Step
We want an exponential model, $B=Ab^{t}$
At the start, $t=0$ hours, and the initial size is $A=1000$
So, $B=1000b^{t}$
Given $(2,1500)$, the $1000$ increases to $1500$ in $t=2$ hours, so we have
$\left\{\begin{array}{l}
1500=1000b^{2}\\
b^{2}=1500/1000=1.5 \\
b=1.5^{1/2}
\end{array}\right\}$
Thus
$B=1000\cdot[(1.5)^{1/2}]^{t}$
$B=1000\cdot[1.5]^{t/2}$
In two days ($t=48$ hrs) there will be
$B=1000(1.5)^{48/2}=16,800,000$ bacteria
