Boutique Chocolate Truffles, a family-owned business, has an opportunity to supply its product for distribution through the Starbucks chain. However, Starbucks has certain specifications regarding cacao content as it wishes to advertise the health benefits (antioxidants) of the chocolate products it sells. In order to determine the mean % cacao in its dark chocolate products, quality Inspectors sample 28 pieces. They find a sample mean of 55% with a standard deviation of 4.7%. What is the margin of error at 95% confidence? 18% O 24% O .5% O.9%