(Use 5-Button Solution) Sam may upgrade his electric heating system to a natural gas unit. The investment will be $3000 installed. Assume the interest rate is 9% per year. (a) If Sam wants to recover the initial investment within two year, the monthly cost saving must be no less than $ (Rounding answer to the nearest dollars) (b) If the cost of the natural gas will average $90 per month over the year, instead of the $200 per month that the electricity costs. It will take months to recover the initial investment? (Rounding up the answer to the nearest whole months)
