If a bacteria culture starts with 8000 bateria and doubles every 25 minutes, how many minutes will it take the population to reach 43000?

i need help setting up this problem, formula: y = Ce^(kt)

so far i have 43000 = 8000e^(25)k

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- January 25th 2007, 06:26 PMvietexponential growth
If a bacteria culture starts with 8000 bateria and doubles every 25 minutes, how many minutes will it take the population to reach 43000?

i need help setting up this problem, formula: y = Ce^(kt)

so far i have 43000 = 8000e^(25)k - January 25th 2007, 06:44 PMviet
ok here what i gotten sofar:

43000 = 8000e^(25t)

(43/8) = e^(25t)

ln(43/8) = 25t

(ln(43/8)) / 25 = t

so t = 0.67270 approx.

not sure what im doing wrong but the answer is wrong :confused: - January 25th 2007, 06:53 PMthedoge
you are in my calc II class too?

No calcs=an adjustment. Kind of stupid to require that when it is obvious you need them for the homework.

i think i finally realize i need to get a tutor. i do everything exactly like i think I should, but my answers are hit or miss. it's so frustrating not knowing the one error you are making.

I don't know about this problem either. I thought I had it but my answers aren't working.

BTW, I am doing it exactly like you. - January 25th 2007, 07:08 PMviet
yeah.. this class sucks. she doesnt allow notes on the test, so im going to be screwed cuz i dont have a good memory.

- January 25th 2007, 07:11 PMthedoge
Yeah, same. As bad as our last teacher taught in class at least he compensated for it on his tests. This teacher is fairly good, but she is a harder teacher. I always feel like I have this stuff down until webwork or a quiz comes, then I think I don't know it at all.

- January 25th 2007, 08:03 PMThePerfectHacker
You guys in the same class?

What chances are this of happening :rolleyes: - January 25th 2007, 08:08 PMthedoge
Yep. We had the same teacher last semester as well as this semester. There is actually a third person in the same situation that comes here :)

for future reference, the general formula to solve this is

Pf=Po*e^(kt)

k=ln(2)/(doublingtime)

solve for t - January 27th 2007, 12:08 PMearboth