Final answer:
To correctly find the interest earned with compound interest, we need to know the principal amount and the frequency at which interest is compounded.
Step-by-step explanation:
To find the interest earned on a deposit with compound interest, we need to use the formula for compound interest rather than simple interest. In this case, the principal amount is not stated, so assuming a principal of $100, similar to the example provided, and an interest rate of 3.5% compounded annually (which may differ depending on how interest is actually compounded in the problem), we can estimate the interest earned over a period from February 9th to April 15th, which is approximately 2 months or ⅓ of a year.
However, without additional information such as the compound frequency (annually, monthly, daily, etc.) and the exact principal amount, it is impossible to accurately calculate the interest earned over this time period. To solve for the correct interest value, the formula typically used is:
A = P (1 + rac{r}{n})^{(nt)}