The City of Salem parks department is considering the purchase of a new, more efficient pool heater for its Campbell Swimming Pool at a cost of $20,000. It should save $4,000 in cash operating costs per year. Its estimated useful life is 8 years, and it will have zero disposal value. Ignore taxes. (Click the icon to view the present value factor table (Click the icon to view the present value annuity factor table.) Read the Requirement 1. What is the payback time? Begin by selecting the formula and then entering the amounts to calculate the payback period. (Round the payback to the nearest whole number.) Requirement 2. Compute the NPV if the required rate of return is 10%. Should the department buy the heater? Why? Begin by calculating the net present value (NPV) of the proposed investment. (Enter the present value factor to four decimal places, "X.XXXX." Round dollar amounts the nearest whole number. Use a minus sign or parentheses for a negative net present value.) Should the City of Salem parks department buy the heater? Why? Salem City parks department should the proposal because the NPV is Requirement 3. Using the ARR model, compute the rate of return on the initial investment. (Assume Salem uses the initial investment [and not average initial investment] when calculating its ARR. Enter ARR as a percentage rounded to the nearest tenth of a percent, X.X\%. Use a minus sign or parentheses for a negative ARR.)