Sal currently has an account balance of $ 2,835.48. he opened the account five years ago with a deposit of $2,310.72. if the interest compounds twice a year, what is the interest rate on the account?

Exp = log (total/principal) / n*years
where n is compounding periods per year (2)
exp = log (2,835.48 / 2,310.72) / 2 * 5
exp = log( 1.2270980474 ) / 10

exp =  0.088879265045 / 10
exp =  0.0088879265045

rate = (10^exp -1) * n
rate = 1.0206760553  -1 * n
rate = .0206760553 * 2

rate = 0.0413521106
rate = 4.13521106 %
Use this calculator to check it:
http://www.1728.org/compint.htm
 

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