Please answer A-B with the corresponding interest.

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Suppose you invest $1,200 in an account paying 7% interest per year. a. What is the balance in the account after 4 years? How much of this balance corresponds to "interest on interest"? b. What is the balance in the account after 30 years? How much of this balance corresponds to "interest on interest"? a. What is the balance in the account after 4 years? The balance in the account after 4 years is $ (Round to the nearest cent.)