Answer:
The critical value for this hypothesis test is 6.571.
Step-by-step explanation:
In this case the professor wants to determine whether the average number of minutes that a student needs to complete a statistics exam has a standard deviation that is less than 5.0 minutes.
Then the variance will be,
The hypothesis to determine whether the population variance is less than 25.0 minutes or not, is:
<em>H</em>₀: The population variance is not less than 25.0 minutes, i.e. <em>σ²</em> = 25.
<em>Hₐ</em>: The population variance is less than 25.0 minutes, i.e. <em>σ²</em> < 25.
The test statistics is:
The decision rule is:
If the calculated value of the test statistic is less than the critical value, then the null hypothesis will be rejected.
Compute the critical value as follows:
*Use a chi-square table.
Thus, the critical value for this hypothesis test is 6.571.
