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a savings account is started with an initial deposit of $600. the account earns 2.1 % interest compounded annually.
(a) write an equation to represent the amount of money in the account as a function of time in years.

(b) find the amount of time it takes for the account balance to reach $800. show your work.

Part a)  

Part b)

Step-by-step explanation:

Part a)

we know that    

The compound interest formula is equal to  

where  

A is the Final Investment Value  

P is the Principal amount of money to be invested  

r is the rate of interest  in decimal

t is Number of Time Periods  

n is the number of times interest is compounded per year

in this problem we have  

substitute in the formula above

Part b) For

substitute in the expression

simplify

Apply log both sides