10. A Consol (perpetuity) will start paying $140 at the end of 5 years. What is the value of the consol today if the discount rate is 7%?

15. If you earn 10% per year on your bank account, how long will it take an account with $105 to double to $210?

18. Professors Annuity Corp. offers a lifetime annuity to retiring professors. For a lump payment today of $81,063.64, the firm will pay the retiring professor a set amount of money per year for 20 years. If the interest rate on the annuity is 2.5%, then what are the annual payments?

20.

You believe you will spend $41,000 a year for 19 years once you retire in 38 years. If the interest rate is 7% per year, how much must you save each year until retirement to meet your retirement goal? (Do not round intermediate calculations. Round your answer to 2 decimal places.)

Annual savings

$