Moresan Co$,$ gathered the following information on power costs and factory machine usage for the last six months:MonthPower CostFactory Machine HoursJanuary$1$$$24\mathrm{.}40013,900$February$30,40017\mathrm{.}600$March$29,00016\mathrm{.}800$April$22\mathrm{.}34013,200$May$19\mathrm{.}90011,600$June$16,9008,600$Using the high$-$low method of analyzing costs, answer the following questions and show computations to support your answers.$($a$)$What is the estimated variable portion of power costs per factory machine hour? $($Round answer to $2$ decimal places, eg$.15\mathrm{.}25.)$