Drugs Online $($DO$)$ is an online retailer of prescription drugs and health supplements. Vitamins represent a significant percentage of its sales. Demand for vitamins is $10,000$ bottles per month. DO incur a fixed order placement, transportation, and receiving cost of $$100$ each time an order for vitamins is placed with the manufacturer. DO incur a holding cost of $20$ percent. The price charged by the manufacturer follows the all$-$unit discount pricing schedule shown following. Evaluate the number of bottles that the DO manager should order in each lot.

$[15$ Marks$]$

Schemes

Order Quantity

Unit Price

Scheme $1$

$0-10000$

$$3\mathrm{.}00$

Scheme $2$

$10,000-25000$

$$2\mathrm{.}95$

Scheme $3$

$25,000$ or more

$$2\mathrm{.}90$