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9. A bacteria population, , can be represented by the equation p= 100,000 times(1/4)^d,
where d is the number of days since it was measured.
a. What was the population 3 days before it was measured? Explain how you
know.
b. What is the last day when the population was more than 1,000,000? Explain how
you know.

Respuesta :

#1

  • 3days back means 3

Put it

[tex]\\ \rm\Rrightarrow p=100000(0.25)^{3}[/tex]

[tex]\\ \rm\Rrightarrow p=100000(0.015625)[/tex]

[tex]\\ \rm\Rrightarrow p=1562.5[/tex]

Now

#2

Let's see

[tex]\\ \rm\Rrightarrow 100000(0.25)^d=1000000[/tex]

[tex]\\ \rm\Rrightarrow 0.25^d=10[/tex]

[tex]\\ \rm\Rrightarrow ln0.25^d=ln10[/tex]

[tex]\\ \rm\Rrightarrow dln0.25=2.3[/tex]

[tex]\\ \rm\Rrightarrow d(-1.39)=2.3[/tex]

[tex]\\ \rm\Rrightarrow d=-1.654[/tex]