$15.$ A manufacturer of exercise equipment purchases the pulley section of the equipment from a supplier who lists these prices: less than $1,000,$ $$5$ each; $1,000$ to $3,999,$ $$4\mathrm{.}95$ each; $4,000$ to $5,999,$ $$4\mathrm{.}90$ each; and $6,000$ or more, $$4\mathrm{.}85$ each. Ordering costs are $$50,$ annual carrying costs per unit are $40$ percent of purchase cost, and annual usage is $4,900$ pulleys.asd business simulation