A quantity with an initial value of 830 grows exponentially at a rate such that the quantity doubles every 2 weeks. What is the value of the quantity after 21 day, to the nearest hundredth?

Answer :

Answer:

The value of the quantity after 21 days is 2,347.59.

Step-by-step explanation:

The exponential growth function is

[tex]A=A_0(1+r)^t[/tex]

A= The number of quantity after t days

[tex]A_0[/tex]= initial number of quantity

r= rate of growth

t= time in days.

A quantity with an initial value of 830 grows at a rate such that the quantity doubles in 2 weeks = 14 days.

Now A= (2×830)= 1660

[tex]A_0[/tex] = 830

t = 14 days

r=?

Now plug all value in exponential growth function

[tex]1660=830(1+r)^{14}[/tex]

[tex]\Rightarrow \frac{1660}{830}= (1+r)^{14}[/tex]

[tex]\Rightarrow 2= (1+r)^{14}[/tex]

[tex]\Rightarrow (1+r) ^{14}=2[/tex]

[tex]\Rightarrow (1+r)=\sqrt[14]{2}[/tex]

[tex]\Rightarrow r=\sqrt[14]{2}-1[/tex]

Now, to find the quantity after 21 days, we plug [tex]A_0[/tex] = 830, t= 21 days in exponential function

[tex]A=830( 1+\sqrt[14]{2}-1)^{21}[/tex]

[tex]\Rightarrow A=830(\sqrt[14]2)^{21}[/tex]

[tex]\Rightarrow A=830(2)^\frac{21}{14}[/tex]

[tex]\Rightarrow A=830(2)^\frac{3}{2}[/tex]

[tex]\Rightarrow A=2,347.59[/tex]

The value of the quantity after 21 days is 2,347.59.

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