SOLUTION: The count in a bacteria culture was 600 after 10 minutes and 2000 after 35 minutes. Assuming the count grows exponentially, What was the initial size of the culture? Fi

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Question 1159189: The count in a bacteria culture was 600 after 10 minutes and 2000 after 35 minutes. Assuming the count grows exponentially,
What was the initial size of the culture?

Find the doubling period.

Find the population after 120 minutes.

When will the population reach 10000

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
The count in a bacteria culture was 600 after 10 minutes and 2000 after 35 minutes.
Assuming the count grows exponentially,
Using the form that a*b^x = y
x=10, y=600
a%2Ab%5E10+=+600
a+=+600%2Fb%5E10
x=35, y=2000
a%2Ab%5E35+=+2000
replace a with 600%2Fb%5E10
%28600%2Fb%5E10%29%2Ab%5E35+=+2000
cancel b^10
600%2Ab%5E25+=+2000
b%5E25+=+2000%2F600
b%5E25+=+20%2F6
25%2Aln%28b%29+=+ln%283.333%29
ln(b) = ln(3.333)/25}}}
ln(b) = .048159
b = 1.049337
Find a
a = 600%2F1.048337%5E10
a = 600%2F1.6186
a = 370.7
The equation
y+=+370.7%2A1.049337%5Ex%29
:
What was the initial size of the culture?
x=0, therefore 370.7 is the initial amt
:
Find the doubling period.
1.049337%5Ex+=+2
x*ln(1.049337) = ln(2)
x+=+ln%282%29%2Fln%281.049337%29
x = 14.4 min
:
Find the population after 120 minutes.
y+=+370.7%2A1.049337%5E120%29
y = 370.7*323.443
y = 119,900.5
:
When will the population reach 10000
370.7%2A1.049337%5Ex+=+10000
1.049337%5Ex+=+10000%2F370.7
1.049337%5Ex+=+26.976
x*ln(1.049337) = ln(26.976)
x+=+ln%2826.976%29%2Fln%281.049337%29
x = 68.42 min
:
looks like this
+graph%28+300%2C+200%2C+-50%2C+150%2C+-20000%2C+100000%2C+370.7%2A1.049337%5Ex%29+