How much would you have to invest today to receive the following? Use Appendix B and Appendix D for an approximate answer, but calculate your final answer using the formula and financial calculator methods.

$$15,000$ in $8$ years at $10$ percent.

Note: Do not round intermediate calculations. Round your final answer to $2$ decimal places.

$$20,000$ in $12$ years at $13$ percent.

Note: Do not round intermediate calculations. Round your final answer to $2$ decimal places.

$$6,000$ each year for $10$ years at $9$ percent.

Note: Do not round intermediate calculations. Round your final answer to $2$ decimal places.

$$50,000$ each year for $50$ years at $7$ percent.

Note: Do not round intermediate calculations. Round your final answer to $2$ decimal places.