A professor would like to test the hypothesis that 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. A random sample of 15 students was selected and the sample standard deviation for the time needed to complete the exam was found to be 4.0 minutes. What would be the number of degrees of freedom for this hypothesis test?

The number of degrees of freedom for this hypothesis test is 14.

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:

H₀: The population variance is not less than 25.0 minutes, i.e. σ² = 25.

Hₐ: The population variance is less than 25.0 minutes, i.e. σ² < 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.

Here,

α = level of significance

(n - 1) = degrees of freedom

The degrees of freedom is the number of values that can change throughout a statistical hypothesis test.

Compute the degrees of freedom as follows:

Thus, the number of degrees of freedom for this hypothesis test is 14.

so a parallelogram is just like a square base times height. multiply 40 and 39 to get 1560 inches.

a triangle is base times height divided by two. so multiply 7.9 and 5 and then divide it by 2 to get 19.75inches.

the kite can be split into two separate triangles and added together to get the total area. 30 x 4 /2 which equals 60. make sure to double it for the two triangles making 120.