$91$ point

Use the following problem to answer the next $9-20$ questions.

A retail drug chain purchases a newly developed drug in pill form from a pharmaceutical firm and sells it to the public. During FDA testing, it was determined that the drug's active ingredient expires quickly and the retailer can't sell pills which are purchased more than $30$ days earlier. The selling price per $30-$day supply $($bottle$)$ of pills is $$250.$ Unsold pills have no value and are disposed of at no cost$.$

The marketing forecast for sales is $50,000$ bottles per month with standard deviation of $8,000,$ distributed normally. The pharmaceutical firm sells the drug to the retail chain for $$90$ per bottle.

What is the cost of underage $($underestimating demand$)$ by one bottle of the drug?