Given 1000 bacteria cells with a percentage decay rate of −1.5%. Write a function based on the situation:

Answer 1

If you take away 1.5%, you're left with 98.5%, right?

Let's say it's per day. After 1 day, you have 1000(0.985), aka 1000(0.985)¹. After 2 days you have 1000(0.985)(0.985), aka 1000(0.985)², etc.

This also leads to the starting point, which we call day 0, so you have 1000(0.985)⁰. Since anything to the zero power equals 1, that gives us our starting value of 1000.

Soooo, if we say n = the time unit (hour, day, week, whatever), then...

f(n) = 1000(0.985)ⁿ

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