1) You estimate that by the time you retire, you will have accumulated $1.8mln in savings. If the interest rate is 4% and you live 30 years after retirement, what annual level of expenditure will those savings support?

And what if,

2) Youre saving for retirement. You think you need an income of $80,000 per year for 30 years after retirement and you have 40 years to go until retirement. How much money would you need to have saved today to not need to contribute any more money for the next 40 years if the interest/investment rate is 8% both before and after retirement?