19-->23 plz

19. Lai's great aunt left him $20,000 when she died. He can invest the money to earn 12% per year. If he spends $3,540 per year out of this inheritance, how long will the money last? 20. Mai has three personal loans outstanding to her friend. A payment of $1000 is due today, a $500 payment is due one year from now and a $250 payment is due two years from now. She would like to consolidate the three loans into one, with thirty-six equal monthly payments, beginning one month from today. Assume the agreed interest rate is 8% (effective annual rate) per year. How large will the new monthly payment be? 21. Larry's bank account has a "floating" interest rate on certain deposits. Every year the interest rate is adjusted. Larry deposited $20,000 three years ago, when interest rates were 7% (annual compounding). Last year, the rate was only 6%, and this year the rate fell again to 5%. How much will be in his account at the end of this year? 22. A local bank advertises the following deal: "Pay us $100 a year for 10 years and then we will pay you (or your beneficiaries) $100 a year forever". Is this a good deal if the interest rate available on other deposit is 6%? 23. A local bank will pay you $100 a year for your lifetime if you deposit $2,500 in the bank today. If you plan to live forever, what interest rate is the bank paying