FedEx matches employee contributions to a Health Savings Account on a 1:1 or dollar for dollar basis. For example, if the employee contributes $50, the company contributes $50. If the employee contributes $125, the company contributes $125.

4A. Assume contributions (i.e. deposits) are made monthly, and the account earns 12.0% interest per year, compounded quarterly. What is the effective interest rate per time unit?

4B. If Marie, a FedEx employee, wants to have $5,136 in her HSA at the end of 8 years from now (including both her contributions and the match), what amount does she need to deposit into her account at the end of each month? Assume the effective interest rate is 2.8% per quarter.