Question

A bacteria culture begins with 15 bacteria which double in amount at the end of every hour. How many bacteria are grown during the 12th hour?
30,720
782,580
7,971,615
23,914,845

Answer 1

We use P = i•e^rt for exponential population growth, where P = end population, i = initial population, r = rate, and t = time
P = 2•i = 2•15 = 30, so 30 = 15 [e^(r•1)],
or 30/15 = 2 = e^(r)
ln 2 = ln (e^r)
.693 = r•(ln e), ln e = 1, so r = .693
Now that we have our doubling rate of .693, we can use that r and our t as the 12th hour is t=11, because there are 11 more hours at the end of that first hour
So our initial population is again 15, and P = i•e^rt
P = 15•e^(.693×11) = 15•e^(7.624)
P = 15•2046.94 = 30,704

Answer 2

Answer:

30,720

Step-by-step explanation:

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