A building contractor subcontracts to a local merchant a job involving hanging wallpaper. To have an idea of the quality level of the merchant's work, the contractor randomly selects 300 m2 and counts the number of blemishes. The total number of blemishes for 30 samples is 80. Construct the centerline and control limits for an appropriate chart. Is it reasonable for the contractor to set a goal of an average of 0.5 blemish per 100 m2?