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A random sample of 100 households was selected as part of a study on electricity usage,...

A random sample of 100 households was selected as part of a study on electricity usage, and the number of kilowatt-hours (kWh) was recorded for each household in the sample for the March quarter of 2016. The average usage was found to be 660 kWh and it was found that the standard deviation of the usage was 80 kWh.

Construct a 90% confidence interval for the mean usage in the March quarter of 2016

Does the data provide significant evidence, at 10% significance level, that the mean usage is greater than 665 kWh?

1. Identify the null and alternative hypotheses:

2. Calculate the z or t value showing how you did so.

3. Does the hypothesized mean fall within the confidence interval you found earlier?

4. Based on your answer to #2 and #3, would you say that the mean usage is greater than 665 kWh? Why or why not?

5. What can be said about the p-value for this hypothesis test? (No need to find the p-value, what can be said about it based on your previous answers)

math   Statistics-And-Probability   
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