SOLUTION: the number of rabbits in a certain population doubles every month and there are 20 rabbits present initially. Express the number of rabbits as a function of time.

Question 1074411: the number of rabbits in a certain population doubles every month and there are 20 rabbits present initially. Express the number of rabbits as a function of time.
Answer by Theo(13342) (Show Source): You can put this solution on YOUR website!
f = p * (1 + r) ^ n
f is the future value of the number of rabbits.
p is the present value of the number of rabbits.
r is the growth rate per month.
n is the number of months.

you are given that p = 20 and that r = 1

the formula becomes:

f = 20 * (1 + 1) ^ n

simplify this to get f = 20 * 2 ^ n

when n = 0, the number of rabbits is 20 * 2^0 = 20 * 1 = 20
when n = 1, the number of rabbits is 20 * 2^1 = 20 * 2 = 40
when n = 2, the number of rabbits is 20 * 2^2 = 20 * 4 = 80
when n = 3, the number of rabbits is 20 * 2^3 = 20 * 8 = 160

as you can see, the number of rabbits is doubling each month.

that's a 100% increase in the number of rabbits each monthly.
100% would be equal to r%.
to get 4, divide that by 100 to get r = 1

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