SOLUTION: The count in a bacteria culture was 200 after 15 minutes and 2000 after 40 minutes. Assuming the count grows exponentially, what is the doubling period?

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Question 1147675: The count in a bacteria culture was 200 after 15 minutes and 2000 after 40 minutes. Assuming the count grows exponentially,
what is the doubling period?

Found 2 solutions by josmiceli, ikleyn:
Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website!

and

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divide both sides by

Take the log base 10 of both sides

( I'll refer back to this step )

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To find doubling period:

Take log base 10 of both sides
( from the above mentioned step )

The doubling period is 7.526 min
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Get another opinion if needed

Answer by ikleyn(52890) (Show Source):
You can put this solution on YOUR website!
.

The shortest way to solve the problem is THIS: = 10 = . Take logarithm base 2 of both sides. = t Find by any way you can. // I use my MS Excel in my computer, as always. t = 3.32. Thus 40-15 = 25 minutes is 3.32 times the doubling period. Hence, the doubling period is = 7.5 minutes (approximately). ANSWER

Solved.