Consider the following mortgage pool: Mortgage#1 15-year 4% annual interest rate with $0.5m principle; Mortgage #2 30-year 3.5% annual interest rate with $0.8m principle; Mortgage #3 15-year 5% annual interest rate with $1m principle.

All three mortgages are just initiated, so they all have their full terms left.

Suppose this pool is divided into 50 "shares". Calculate the monthly cash flow received for owning each share. The actual amount received by end-investors is going to be lower than the theoretical value you calculate. Briefly explain why.