P17 用去年的钱计算实际收益率(可汗学院《宏观经济学》)

in last vedio we were able to claculate the real return by putting everything in today's dollars

put that 100 dollars investmest a year ao in today's dollars

figure out what our actual return was our dollar return is in today's dollars

we can put everything in last year's money

let us put 100 dollars of today's money in last year's money

and to think about this we can do a little algebra that makes a little bit more intuitive

there is some amount of money last year let us call that x

if we multiply it by the inflation rate growth by 2%

that is going to be worth 110 dollars today

or to solve for x just divide both sides by 1.02

we get the amount of money that if you grow it by inflation or that had the same amount of pruchasing power as 110 dollars today

would be 110 divided by 1.02 which is 107.84 just roughly just round it

so this is equal to 107.8

so 110 dollars today buys exact the same thing as 107.8 would have bought us last year

so what is our dollar return in last year's money

the real return how much our actual purchasing power increaed

we got 7.84 dollar return off of 100 dollar investment