David Polston prints up T-shirts to be sold at local con certs. The T-shirts sell for $20 each but cost David only $6.50 each. However, because the T-shirts have concert-specific information on them, David can sell a leftover shirt for only $3. Suppose the demand for shirts can be approximated with a normal distribution and the mean demand is 120 shirts, with a standard deviation of 35. What is the target service level? How many shirts should David print up for a concert?