nominal annual rate

You are facing two business opportunities with the following cash flows:
a. Investing $10,000 today, receiving $5,000 after three months, $4,500 after six months, and another $4,500 nine months from today.
b. Alternatively, you can invest $11,480 today, and receive $5,500, $5,000, and $5,000 after three, six, and nine months. What is the better investment for you, a or b? Assume that the nominal annual rate is 5%, and compounding is done quarterly.