Cullumber Co. gathered the following information on power costs and factory machine usage for the last six months: Factory Machine Month Power Cost Hours January $29,650 16,400 February 37,885 22,600 March 34,125 19,300 April 27,465 15,700 May 25,150 14,100 June 21,900 11,100 Using the high-low method of analyzing costs, answer the following questions and show computations to support your answers. What is the estimated variable portion of power costs per factory machine hour? (Round answer to 2 decimal places, e.g. 15.25.) Variable power costs $ per factory machine hour