Question

A power supply company states that it has a target power supply of 119 volts. A researcher wants to test the company’s claim so she collected data from 30 random family homes and calculated the following sample statistics: x ̅=118.89 volts,s=0.35 volts. Use a 0.01 significance level to test the claim that the mean power supply is 119 volts.

1. Identify the null and alterative hypotheses, test statistic, and P-value. Round to three decimal places.
2. State te final conclusion that addresses the original claim

Answer 1

a) As we are testing whether the mean power supply is 119 volts, the null and the alternate hypothesis here are given as:

The test statistic here is computed as:

As this is a two tailed test, the p-value here is computed as:

For n-1 = 29 degrees of freedom, we get from the t distribution tables:

Therefore 0.096 is the required p-value here.

b) As the p-value here is 0.096 > 0.01 which is the level of significance, therefore the test is insignificant and we cannot reject the null hypothesis here, therefore we dont have sufficient evidence to reject the claim that the mean power supply is 119