Problema Solution

The number of bacteria N in a culture is modeled by N(t)=200e^kt where t is the time in hours. If N=500 when t=3, what is the time required for the original population to triple in size?

Answer provided by our tutors

N(t)=200e^(kt)


N(3) = 500


200e^(k*3) = 500


First we will find k by solving:


200e^(k*3) = 500 divide both sides by 200


e^(3k) = 2.5


(e^k)^3 = 2.5


Let t represent the time in hours needed for the original population to triple in size:


N(t) = 3N(0)


200e^(kt) = 3*200e^(k*0)


200e^(kt) = 600 divide both sides by 200


(e^k)^t = 3


(e^k)^(3t) = 3^3


((e^k)^3)^t = 27


2.5^t = 27

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t = 3.6 hr


The time required for the original population to triple in size is 3.6 hours.