送交者: mangolasi 于 2005-3-22, 19:03:44:
回答: Yes. We are talking a small project not national 由 skipper3 于 2005-3-22, 18:46:48:
about the time value of money (rule of thrumb in finance). Maybe I miss something, but if you think after counting inflation of something, 900k will worth only 133k is deadly wrong. Worse than 900k worth only 900k after 50 years.
If there is no inflation, and you put the money into the bank w/ interest i_1, then your house worth 900k today will worth 900k*(1+i_1)^50 in 50 years. If i_1 is your nomial interest rate(you have a CD of 50 years), and the inflation is i_2, roughly, your 900k today will worth 900k*(1+i_1-i_2)^50.
So usually you pay the interest for the house roughly i_3, the money you earn from the house can be roughly, if you pay a lump_sum interest at the end (I forgot the formula for each period payment) would be 900k*(i_3-i_2)^50. Then you earn/lose money is roughly 900k*(i_1-i_2)^50-900k*(i3-i_2)^50+(rent accumulated w/interest rate i_1). Usually we suggest people to have mortgage while could afford buying house through one payment only when you have better return of your money than the mortgage rate.