math
The rate of increase of bacteria in a culture is proportional to the number of bacteria present .if the original number of bacteria double in the two hours, in how many hours will it be five times?
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manisha

this is exponential growth. Since it doubles in 2 hours, the population is after t hours is
p(t) = A*2^(t/2)
So, it will be 5 times as big as at first when
2^(t/2) = 5
or, you can start from scratch, using
dp/dt = kp
dp/p = k dt
lnp = kt+lnA
p = A*e^(kt)
and work it from thereposted by Steve
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