Using a financial calculator, how do you find the answer?

1. A gold mine is expected to bring $10,000 a year for the first 10 years, and $5,000 per year for the 2^nd 10 years. Also, it will require $30,000 outlay to properly close the mine at the end of 20 years. If you want 20% rate of return on this investment, how much money is the present value of the mine?

ANSWER: PV= $44,539

2. At a growth rate of 8%, how long does it take a sum to double?

ANSWER: n=9