Select the correct answer. The probability of a student scoring 75% in class work is 0.64, and the probability of a student scor

Answer:

Step-by-step explanation:

Given data and notation

indicates the sample mean

refers to the sample standard deviation

is the sample size

represents the value we are testing.

indicates the significance level for the hypothesis test.

t refers to the statistic of interest.

is the p-value for the test (the variable we are interested in).

Formulate the null and alternative hypotheses.

I will set up the hypotheses to verify if the mean weight falls below 4 ounces, formalizing:

Null hypothesis:

Alternative hypothesis:

Since our sample size is < 30 and the population standard deviation is unknown, it’s advisable to utilize a t test to compare the actual mean against the reference value, with the statistic calculated as follows:

(1)

t-test: "This test compares group means and is commonly utilized to determine if the mean is (greater than, less than, or not equal to) a specific value."

Calculate the statistic

We can substitute the provided information into formula (1):

Answer:

a) Null and alternative hypothesis

b) Point estimate d = -$78

c) Test statistic t = -2.438

P-value = 0.0113

Reject H0. This indicates that the average automobile premium in Pennsylvania is lower than in the nation.

Step-by-step breakdown:

This is a statistical test for the average population mean.

The hypothesis posits that car insurance in Pennsylvania is notably less expensive compared to the national average.

Accordingly, the null and alternative hypotheses are:

The significance level is set at 0.05.

The sample size is n=25.

The sample mean equates to M=1425.

A point estimate of the difference between the Pennsylvania mean premium and the national average can be computed using the sample mean:

Given that the standard deviation of the population is unknown, we approximate it using the sample standard deviation, which is s=160.

Then, we can calculate the t-statistic as:

The degrees of freedom for this sample size stand at:

This constitutes a left-tailed test, with 24 degrees of freedom and t=-2.438, rendering the P-value as (per a t-table):

As the P-value (0.0113) falls below the significance level (0.05), the results prove significant.

Thus, the null hypothesis obtains dismissal.

At a 0.05 significance level, there's sufficient evidence to assert that car insurance in Pennsylvania costs notably less than the national average.