Question

Researchers recorded that a certain bacteria population declined from 110,000 to 400 in 30 hours. At this rate of decay, how many bacteria will there be in 19 hours? Round to the nearest whole number.

Answer 1

3137

Explanation:

The decay factor is 400/110,000 = 1/275 in 30 hours. Assuming an exponential decay, the equation for the number remaining can be ...

n(t) = 110,000·(1/275)^(t/30)

Then after 19 hours, the number remaining is ...

n(19) = 110,000·(1/275)^(19/30) ≈ 3137

There will be about 3137 bacteria after 19 hours.