1) What is the present worth of the total 20 payments, occurring at the end of every four months (i.e. the first payment is in four months), which are $400, $500, $600, increasing by a fixed sum. Interest is 10% nominal per year, compounded weekly.

2) Octavia is looking at an investment in upgrading an inspection line at her plant. The initial cost would be $150,000 with a salvage value of $40,000 after five years. How much money must be saved every year to justify the invest at an interest rate of 15%?

3) Octavia is looking at an investment in upgrading an inspection line at her plant. The initial cost would be $150,000 with a salvage value of $40,000 after five years. How much money must be saved every year to justify the invest at an interest rate of 15%?