The Average Natural Gas Bill for a Random Sample of 26

Multiple Choice

The average natural gas bill for a random sample of 26 homes in the 19808 zip code during the month of March was $305.30 with a sample standard deviation of $46.50. The 80% confidence interval around this sample mean is ______ .

A) ($293.30, $317.30)
B) ($268.82, $341.78)
C) ($277.94, $332.66)
D) ($287.06, $323.54)