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Calculating a t interval for a mean

You might need: Calculator,t table

Problem

An economist studying fuel costs wants to estimate the mean price of gasoline in her state on a certain day. On that day, she takes an
of 12 gas stations and finds the sample mean price (in dollars per gallon) is x¯=$2.29 with a standard deviation of sx=$0.20. The prices in the sample are roughly symmetric with no distinct outliers.
Based on this sample, which of the following is closest to a 90% confidence interval for the mean price of gasoline that day in her state?
Choose 1 answer:
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