Part IV Wait Time $(18$ points $-20$ minutes$)$

Norton's Convenience store has a variable demand. The daily demand ranges from $270$ to $330$ customers a day who average purchasing $5$ items each. The average daily demand is $300$ customers. The convenience store currently operates $12$ hours a day. Each order takes approximately $2$ minutes.

Wait time formula:

Average Daily Number of Customers x $($Average Minutes per Order$){?}^2$

$2x[$Daily Capacity in Minutes $-($Avg$.$ Daily No$.$ of Customers x Avg Min. per Order$)]$

Required:

a$.$ What is the average customer waiting time, in minutes?

b$.$ Norton has decided that the waiting time is too long and has increased the hours the store is open to $15$ hours. What is the waiting time now?