Sally's Silk Screening produces specialty T-shirts that are primarily sold at special events. She is trying to decide how many to produce for an upcoming event. During the event, Sally can sell T-shirts for $35 apiece. However, when the event ends, any unsold T-shirts are sold for $7 apiece. It costs Sally $14 to make a specialty T-shirt. Sally's estimate of demand is the following: a. What is the service rate (or optimal fractile)? (Round your answer to 2 decimal places.) b. How many T-shirts should she produce for the upcoming event