The following data is the result of a random sample of the ages (in years) of 12 houses in a community: 18, 22, 23, 19, 18, 24, 26, 17, 12, 27, 28. Construct a 90% confidence interval for the mean age of a house in this community.
You will need to calculate the mean and standard deviation, then use a confidence formula to determine the interval.
Here is a formula to use:
CI90 = mean + or - 1.645(sd/√n)
Substitute the values into the formula and calculate.