Marshall Co. produced a pilot run of ninety units of a recently developed piston used in one of its products. Marshall expected to produce and sell 1,900 units annually. The pilot run required an average of 0.55 direct labor hours per piston for 90 pistons. Marshall experienced an seventy percent learning curve on the direct labor hours needed to produce new pistons. Past experience indicated that learning tends to cease by the time 1,440 pistons are produced. Marshall's manufacturing costs for pistons are presented below. Direct labor Variable overhead Fixed overhead Materials $14.00 per direct labor hour 11.00 per direct labor hour 20.00 per direct labor hour 6.00 per unit Marshall received a quote of $9 per unit from Kytel Machine Co. for the additional 1,810 needed pistons. Marshall frequently subcontracts this type of work and has always been satisfied with the quality of the units produced by Kytel. If the pistons are manufactured by Marshall Co., the average direct labor hours per unit for the first 1,440 pistons (including the pilot run) produced is calculated to be (use five decimal places in calculating the average time)