COMFY SHOES, INC.

Comfy Shoes, Inc. builds shoes tailored to meet each individual customer's needs. Customers

who visit the downtown offices of Comfy Shoes in Philadelphia can choose one or more of the

following four custom$-$tailoring services. Customers receive their shoes in the mail within a week

of their initial visit.

The company offers the following packages to its customers:

Package $1$: Includes only Walking Basics $($Service A$)$

Package $2$: Includes Walking Basics and Walking Plus $($Services A and B$).$

Package $3$: Walking Basics, Walking Plus, and Running Basics $($Services A$,$ B$,$ and C$).$

Package $4$: All four services $($A$,$ B$,$ C$,$ and D$)$

Customers of Comfy Shoes visit the store at a constant rate $($you can ignore any effects of

variability$)$ of $20$ customers per day. Of these customers, $45\%$ buy Package $1,10\%$ buy Package

$2,20\%$ buy Package $3,$ and $25\%$ buy Package $4.$ The mix does not change over the course of the

day. The store operates $12$ hours a day.

What is the implied utilization of the attendant in service $D?$