A sample of bacteria taken from a river has an initial concentration of

$2\mathrm{.}7$ million bacteria per milliliter and its concentration doubles each

week.

$($a$)$ Find an exponential model that calculates the concentration $($in

millions$)$ after $x$ weeks.

$($b$)$ Estimate the concentration $($in millions$)$ after $1\mathrm{.}9$ weeks.

$($a$)B(x)=$

$($Type an equation using $x$ as the variable.$)$

$($b$)$ The estimated concentration of bacteria after $1\mathrm{.}9$ weeks is

million per milliliter.

$($Round to the nearest integer as needed.$)$

Question $4$

Question $5$

Question $6$

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