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 Town A 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

using excel>addins>phstat>one sample t test

we have

t Test for Hypothesis of the Mean
Data
Null Hypothesis                m=	16500
Level of Significance	0.05
Sample Size	250
Sample Mean	14651.548
Sample Standard Deviation	7980.99357
Intermediate Calculations
Standard Error of the Mean	504.7624
Degrees of Freedom	249
t Test Statistic	-3.6620
Lower-Tail Test			Calculations Area
Lower Critical Value	-1.6510		For one-tailed tests:
p-Value	0.0002		T.DIST.RT value	0.000152807
Reject the null hypothesis			1-T.DIST.RT value	0.999847193

since p value is less than 0.05 so we have sufficient evidence to conclude that mean annual energy usage will be below 16,500 kWh per household