A CMO has been issued with 3 tranches and a residual. At origination:

- Tranche A investors own $75 million of principal with a coupon rate of 3.50%.

- Tranche B investors own $31 million of principal with a coupon rate of 3.70%.

- Tranche Z investors own $7 million of principal with a coupon rate of 4.50%.

The residual carries $1 million and receives all residual payments. Mortgages backing the security issued are fully amortizing fixed rate with mortgage rate of 4.50% with 30 year maturities and monthly payments. Assume no servicing/guarantee fee and no prepayments.