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 critical value for a 95% confidence interval around this sample mean is .

2.06

Step-by-step explanation:

The formula for critical value = Margin of Error / Standard Error

Margin of Error = z × Standard deviation/√n

Mean for the month of March = $305.30

Standard deviation = $46.50

n = number of samples = 26 homes

z score for 95% confidence interval = 1.96

= 1.96 × $46.50/√26

= 17.874024556

Standard error = standard deviation/√n

= $46.50/√26

= 9.1194002839

Critical value = Margin of Error/Standard Error

= 17.874024556/9.1194002839

= 2.06