"\\bar x =2.1"
s=2.9
n=278
a) To compute the confidence interval, we use t distribution because the population standard deviation is not provided.
b) 95% confidence interval
"CI=\\bar x \u00b1t_{(n-1, \\frac {\\alpha}{2})}*\\frac{s}{\\sqrt n}"
="2.1\u00b11.96\u00d7\\frac {2.9}{\\sqrt{278}}"
=(1. 759, 2.441)
With 95% confidence the population mean number of visits per week is between 1.759 and 2.441 visits
c)If many groups of 278 randomly selected members are studied, then a different confidence interval would be produced from each group. About 95 percent of these confidence intervals will contain the true population mean number of visits per week and about 5 percent will not contain the true population mean number of visits per week
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