Bacteria grow in a nutrient solution at a rate proportional to the amount present. Initially, there are 250 strands of the bacteria in the solution which grows to 800 strands after seven hours. Find the time needed for the bacteria to grow to 1600 strands.
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Given a starting population of N0, our general expression for exponential growth is N=N0ert
where r is a positive constant. Substituting for the given information, we can find r as follows:
800=250er(7)
3.20=e7r
r=17ln3.2=0.166164
a) A general expression for the number of stands in the culture at any time is N=250e0.166164t
.
b) The time needed for the bacteria to grow to 1,600 strands is therefore:
1600=250e(0.166164)t
6.4=e0.166164t
t=10.166164ln6.4=11.1715
Therefore, it takes 11.17 hours for the population to grow to 1,600 strands.
where r is a positive constant. Substituting for the given information, we can find r as follows:
800=250er(7)
3.20=e7r
r=17ln3.2=0.166164
a) A general expression for the number of stands in the culture at any time is N=250e0.166164t
.
b) The time needed for the bacteria to grow to 1,600 strands is therefore:
1600=250e(0.166164)t
6.4=e0.166164t
t=10.166164ln6.4=11.1715
Therefore, it takes 11.17 hours for the population to grow to 1,600 strands.