A sandwich chain advertises that it has foot-long sandwiches. Wanting to know if this advertisement is accurate, you measured a random sample of forty sandwiches and found the mean length as 11.9 inches and the standard deviation is 0.4 inches. Using the table below, find the 95% confidence interval. 11.78 to 12.02 11.80 to 12.00 11.74 to 12.06 13 Confidence Level (as a percent) -valuez 90 1.645 95 1.960 99 99 2.576