The average monthly gas bill of a random sample of 35 residents of a city is $130 with a standard deviation of $25. Assume the gas bills are normally distributed. Construct a 90% confidence interval...

The average monthly gas bill of a random sample of 35 residents of a city is $130 with a standard deviation of $25. Assume the gas bills are normally distributed. Construct a 90% confidence interval for the population mean monthly gas bills of all residents.