# Precalculus

A savings account starts with \$600 and pays 5% interest per year, compounded four times per year.
a) A function that models the amount in dollars in the bank account after m years is A(m)=____________?
b) How much will be in the savings account after 3 years? \$______?
c) The amount in the account will exceed \$1400 after ________ years.

1. amount = 600(1 + .05/4)^(4m)

b) A = 600(1.0125)^12 = ...

c) set A = 1400
1400 = 600(1.0125)^n, remember n is quarter years.
2.33333 = (1.0125)^n
do you know how to do logs? If so, ..
n = log 2.33333/log 1.0125 = 68.2 quarter years or about 17 years.

notice 17 years ---> n= 68
amount = 600(1.0125)^68 = \$1396.41
so you will need about 68 and 1/4 years.

posted by Reiny

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