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 $16 apiece. However, when the event ends, any unsold T-shirts are sold for $4 apiece. It costs Sally $10 to make a specialty T-shirt. Sally's estimate of demand is the following:

Demand	Probability
300	0.10
400	0.20
500	0.40
600	0.15
700	0.10
800	0.05

a) What is the service rate (Please keep two digits after the decimal and don't omit 0 before the decimal, e.g., 0.39)?

b) How many T-shirts should she produce for the upcoming event?