A refrigerator wall is made of 1 inch thick plywood (k = 0.067Btu/ft h °F), a 1 inch layer of insulation (k = 0.019 Btu/ft h °F), and 3 inch of fiberboard (k = 0.33 Btu/ft h °F). Temperatureinside should be maintained at 33 °F, and outside temperature isusually 75 °F. A fan blowing inside the refrigerator is moving theair rapidly, so that hi = 100 Btu/ft2 h °F while ho = 5 Btu/ft2 h°F. Calculate the overall heat transfer coefficient and the rate ofheat transfer through the refrigerator walls.