5.5+10+7.7+9.8 = 33
So you've put in 330K in three months: most people don't have that much of cash.
Also you get 16 houses yet still has mortgage: many people can't loan more than 4.
If out of the other 12 you get only two mortgage ... again you will still get enough cash.
For the 16th, 1500*12/103000=17% or you called Gross Cash rate. But for 300K mortage (reference to the 2nd example), you are paying out 1,600 a month P&I; 200K is then 1,000 a month assuming 5% rate.
What is your net rate then? ...