Andrew M. answered • 03/23/17

Tutor

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Mathematics - Algebra a Specialty / F.I.T. Grad - B.S. w/Honors

A decrease of 3.5% every two years

equates to a decrease of 1.75% yearly.

So each year the new amount is 98.25%

of the previous year.

P(t) = P

_{0}(.09825)^{t}P(t) = Population at t years

P

_{0}= initial populationAssuming you are saying the initial

population is 80:

P(20) = 80(.09825)

^{20}P(20) = 5.62

We would expect there to be about

6 left after 20 years.