SOLUTION: A survey of 66 randomly selected homeowners finds that they spend a mean of $70 per month on home maintenance. Construct a 99% confidence interval for the mean amount of money spen

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Question 1182811: A survey of 66 randomly selected homeowners finds that they spend a mean of $70 per month on home maintenance. Construct a 99% confidence interval for the mean amount of money spent per month on home maintenance by all homeowners. Assume that the population standard deviation is $12 per month. Round to the nearest cent.
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
the half-interval is z(0.995, df=65)*sigma/sqrt(n)
2.57583*12/sqrt(66)=$3.804 or $3.80
($66.20, $73.80)
Note: if z is rounded, the result may change by a cent.