Step 1 :First, calculate the number of days between February 12 and April 21.
Step 2 :The number of days between February 12 and April 21 is 68 days.
Step 3 :Next, plug the values into the formula for compound interest. The principal P is $6200, the annual interest rate r is 3.5% or 0.035 in decimal form, and the time t is the number of days divided by 365.
Step 4 :Calculate the interest using the formula \(A = P \times (1 + \frac{r}{365})^{365 \times t}\), where A is the amount of money accumulated after n years, including interest.
Step 5 :The amount of money accumulated after 68 days is approximately $6240.56.
Step 6 :Subtract the principal from the accumulated amount to find the interest earned.
Step 7 :The interest earned is approximately $40.56.
Step 8 :Final Answer: The amount of interest earned is approximately \$40.56. So, the final answer is \(\boxed{40.56}\).