Can someone help me out with this please?

An interest rate of 20% per year compounded semiannually is the same as an effective (a) 10% per semiannual period (b) 5% per quarter (c) 20% per year (d) 1.67% per month (e) All of the above Five mutually exclusive revenue projects that have infinite lives are under consideration for increasing productivity in a certain government operation. The total costs ($) and annual benefits ($/yr) of each project are shown below. If the interest rate is 10% per year, which project should be selected? (a) Project A (b) Project B (c) Project C (d) Project D (e) Project E How much could the ABC company afford to spend now to overhaul a manufacturing process if the cost four years from now would be $40,000? Assume the interest rate is 10% per year compounded monthly (a)