Cathy opens a savings account with a deposit of $7,000. She deposits $3,000 a year later, $4,000 a year after that, and $1,000 at the end of the third year. The account grows by an annual effective rate i. Just after Cathy's $1,000 deposit, her balance is $16,000. Find i. (Hint: use CF function in calculator) You are given the following amount function: A (t) = t-4t+12. Determine the effective rate of interest in the 6th year.