Exercise 9-7

Bob Nale is the owner of Nale's Quick Fill. Bob would like to estimate the mean number of gallons of gasoline sold to his customers. Assume the number of gallons sold follows the normal distribution with a populationstandard deviation of 2.50 gallons. From his records, he selects a random sample of 45 sales and finds the mean number of gallons sold is 8.30.

(a)What is the point estimate of the population mean?(Round your answer to 2 decimal places.)

Point estimate

(b)Determine a 95% confidence interval for the population mean.(Round your answers to 2 decimal places.)

Confidence interval of _________and ____________.