Posted by jh on Thursday, March 4, 2010 at 6:11pm.
NEED HELP ASAP PLEASE!!
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.

Precalculus  Reiny, Thursday, March 4, 2010 at 7:24pm
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.