the below questions belongs to "present value ":

question one:$100 at the end of three years is worth how much today, assuming a discount rate of (i) 100% (ii) 10% (iii) 0%

question two:What is the aggregate present value of $500 received at the end of each of the next three years, assuming a discount rate of (i) 4% (ii) 25%

question three:$100 is received at the end of one year, $500 at the end of two years, and $1,000 at the end of three years. What is the aggregate present value of these receipts, assuming a discount rate of (i) 4% (ii) 25%

question four:You need to have $80,000 at the end of 12 years. To accumulate this sum, you have decided to save a certain amount at the end of each of the next 12 years and deposit it in the bank. The bank pays 9% interest compounded annually for long-term deposits. How much will you have to save each year (to the nearest dollar)?