Suppose you have $100 million mortgage-backed security with a 4.5% coupon, with annual cash flows, annual interest payments, and the same prepayment amount each year over the life of the loan. Assume a maturity of 3 years and no amortization. Suppose you use this $100 million to create a fixed-rate sequential CMO with the following balances and coupons:

Bond Balance Coupon

A 30 2.5

B 40 3.5

C 30 4.5

Assuming $30 million prepays each year, what is the weighted average