A supermarket chain is deciding what produce providers to purchase from. A sample of 20 heads of lettuce is selected to estimate the average weight of the lettuce from this provider. The population standard deviation for the weight is known to be 0.2 pounds. The sample of 20 heads of lettuce had a mean weight of 2.2 pounds with a sample standard deviation of 0.1 pounds. Calculate and interpret a confidence interval estimate for the true average weight of all heads of lettuce from this provider. Use a 90% confidence level.