Census tractsare small sections within a county with long codes. North Carolina has over 2000 census tracts. As it is unreasonable for us to work with such a large data set, we will continue to explore food insecurity at the county and zip code levels.

1. As of 2019, the census bureau has the totalnumber of supermarkets by zip code listed for NC (using all establishments). Below is a random sampling the number of supermarkets in 40 zips codes. Find x and Sx. Round to the nearest tenth.

Hint: This is a table so you can copy and paste this into excel. There is a standard deviation formula : =STDEVS(cellA1:cell?).

3	5	5	8
3	5	8	5
7	9	14	10
10	7	3	3
9	7	3	5
6	14	6	4
4	3	5	9
19	9	11	5
7	5	4	11

x = Sx =

1. Since the data consists of n > 30, using your Sx and x, construct a 95% confidence interval to estimate the population mean . Round to the nearest tenth. (Section 7.3)

1. Thanks to Excel, we know the standard deviation of all the zip codes that did have data. Using the sample mean and the population standard deviation of 3.5, construct a 95% confidence interval to estimate . Round to the tenth. (Section 7.3)

1. There were over 1,.3 million people in2018 in NC's 100 counties that were impacted by food insecurity. Assuming that NC counties are a representative sample of all US counties, find, with 99% confidence, the estimate of the population standard deviation given that Sx = 19,154. You will need to use df = 100 as we do not have a df = 99, however n = 100. (Section 7.4)