1. Condence Intervals for Population Means o is unknown To track food costs, the media sometimes reports the cost of purchasing a typical grocery basket of food. The same items are purchased so that food prices can be compared from store to store. Suppose we want to estimate the mean price for a typical grocery basket of food at all of the supermarkets in a specic geographical region of the country. A random sample of twenty of these supermarkets is selected from this region, and the cost for a grocery basket of food is found for each supermarket in the sample. The mean and standard deviation of the costs at the menty supermarkets are i = $129.36 and s = $7.39. Assume the distribution of the costs of a grocery basket full of food at all the supermarkets in the region is normally distributed. Find a 95% confidence interval for the mean cost of grocery basket of food for this region. A farmer's market wants to estimate the mean number of pounds of potatoes it sells per week. A random sample of 1? weeks is selected and the number of pounds of potatoes sold each week is recorded. The sample data are: ? = 1094.0 pounds and s = 1362 pounds. Find a 99% confidence interval to estimate the mean number of pounds of potatoes the market sells each week. Assume that the distribution of number of pounds of potatoes sold per week is normal. A random sample of 25 college students was asked to report the number of hours they slept on the previous night. The sample data are: 37 = 6.64 hours and s = 1.0?5 hours. Find a 96% confidence interval for the mean amount of sleep for all college students. Assume that the distribution of the amounts of sleep is normal