Question

The Excel data for this assignment shows the annual energy usage in kWh for a random sample of 250 detached single-family homes in the Southeast. A contractor building a new housing development in Auburn hypothesizes that mean annual energy usage will be below 16,500 kWh per household. Use the data to run a single mean hypothesis test and calculate a test statistic in Excel. In your method summary, state the hypothesis and your assumptions. In your resulting conclusions, state your conclusion regarding the hypothesis in words, using a 99% confidence level.

The Mean of the data is 14651.548

The Standard Deviation is 7980.99357

Answer 1

Given that,

Sample size, n = 250

Sample mean,

Sample standard deviation,

The null hypothesis is,

The alternative hypothesis is,

The sample size is greater than 30. So, we will use the ''z''-test statistic to calculate the test statistic value:

Excel function for the value of P-value:

''=NORMDIST(-3.662,0,1,1)''

The P-value is less than the 1% level of significance. We reject the null hypothesis at the 1% level of significance. We can conclude that the mean annual energy usage will be below 16,500 kWh per household.