Suppose we have a new type of MBS to accommodate the short-term investor. This new MBS security instrument contains only 5-year mortgages. ACME, a private secondary mortgage market, has pooled together ten $100,000 5-year mortgage loans. Note: To save space in writing out your work, you can scale the ten $100,000 to $100.

Calculate the duration for this MBS pool assuming annual compounding for three years at 10 percent interest which

a. is a "zero-coupon"

b. is an interest-only MBS

c. is fully amortizable over the three years