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# How many days will it take for the fruit flies population to be double, if the rate of growth in a population of fruit flies is 10% per day?

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- llafferLv 75 months agoFavorite Answer
If there is a 10% increase per day, then we can set up this equation:

a(t) = a(1.1)^t

Where "a" is the starting population

a(t) is the population after "t" days

t is the number of days

It doesn't matter what "a" is as long as we double it, then we can solve for t. So let's set:

a = 1

a(t) = 2

Then solve for t:

a(t) = a(1.1)^t

2 = 1(1.1)^t

2 = (1.1)^t

ln(2) = ln[(1.1)^t]

ln(2) = t ln(1.1)

ln(2) / ln(1.1) = t

That's the exact answer. A decimal approximation is:

t = 7.27 days (rounded to 2DP)

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