Question

Researchers recorded that a certain bacteria population declined from 800,000 to 500,000 in 6 hours after the administration of medication. At this rate of decay, how many bacteria would there have been at 24 hours? Round to the nearest whole number

Answer 1

We can assume that the decline in the population is an exponential decay.

An exponential decay can be written as:

P(t) = A*b^t

Where A is the initial population, b is the base and t is the variable, in this case, number of hours.

We know that: A = 800,000.

P(t) = 800,000*b^t

And we know that after 6 hours, the popuation was 500,000:

p(6h) = 500,000 = 800,000*b^6

then we have that:

b^6 = 500,000/800,000 = 5/8

b = (5/8)^(1/6) = 0.925

Then our equation is:

P(t) = 800,000*0.925^t

Now, the population after 24 hours will be:

P(24) = 800,000*0.925^24 = 123,166

Answer 2

122,070 bacteria.

Step-by-step explanation:AA0ktA=500,000=800,000=?=6hours=A0ekt

Substitute the values in the formula.

500,000=800,000ek⋅6

Solve for k. Divide each side by 800,000.

58=e6k

Take the natural log of each side.

ln58=lne6k

Use the power property.

ln58=6klne

Simplify.

ln58=6k

Divide each side by 6.

ln586=k

Approximate the answer.

k≈−0.078

We use this rate of growth to predict the number of bacteria there will be in 24 hours.

AA0ktA=?=800,000=ln586=24hours=A0ekt

Substitute in the values.

A=800,000eln586⋅24

Evaluate.

A≈122,070.31

At this rate of decay, researchers can expect 122,070 bacteria.