1. Income from the mining of mineral deposits usually decreases as the resource becomes more difficult to extract. Determine the future worth in year 7 of a mineral lease that yielded an income of $14,914 in years 1 through 4 and then amounts that decreased by 7.5% per year through year 7. Use an interest rate of 13% per year.

2. Find the present worth in year 0 of $25,000 in year 3 and amounts increasing by 15% per year through year 10 at an interest rate of 8% per year.

3. The annual maintenance cost of an underground tunnel was A1=$27,000 in years 1 through 4 and A2=$36,000 in years 5 through 9. Determine the uniform annual value for 9 years at an interest rate of 9% per year.

4. Recalibration of high precision measuring devices costs $9,000 per year. The machine will need to be recalibrated every year for n2=8 years after n1=6 years of initial purchase. Determine the equivalent present worth of recalibration costs? Assume, i=8%.

5. Two payments of $2,400 each are desired in Year 9 and 10. To be able to pay off this payment, four equal amounts will be deposited in a bank in years 4 through n=7 at an interest rate (i) of 11% per year. Determine the value of the equal amount that should be deposited in a bank in Year 4 to Year 7.