In the course of a month, 120 shopping baskets are pulled aside; there were 24,000 shopping baskets of goods sold during that month. The mean net price error per shopping basket in the sample was -6.81 cents/basket (a net undercharge), with a sample standard deviation of 3.79 cents per basket.
An approximate 95% confidence interval for the net price error per shopping basket of goods sold during the month would extend from (Q23) cents (low) to (Q24) cents (high).