A company announced a 1000 Chips Trial claiming that every 1

A company announced a \'\'1000 Chips Trial,\'\' claiming that every 18-ounce bag of its cookies contained at least 1000 chocolate chips. Students purchased random bags of cookies from different stores and counted the number of chips in each bag. Some of the data is shown below. Complete parts (a) through (c) below. that follows a t-Student\'s model. The histogram is roughly bimodal and symmetric, with no outliers, so one can assume that the data come from a population that follows a Normal model. b) Create a 95% confidence interval for the average number of chips.

Solution

sample mean=1239.1

sample standard deviation =116.7594

sample size n=10

The degree of freedom =n-1=10-1=9

Given a=1-0.95=0.05, t(0.025, df=9)=2.26 (from student t table)

So the lower bound is

xbar -t*s/vn =1239.1 -2.26*116.7594/sqrt(10) =1155.7

So the upper bound is

xbar + t*s/vn=1239.1 +2.26*116.7594/sqrt(10) =1322.5