Question 1

For a one-tailed hypothesis test (upper tail), the p-value is computed to be .034.If the test is being conducted at the 5% level of significance, the null hypothesis

Accepted Answer

The p-value is less than the level of significance of 5%, indicating strong evidence against the null hypothesis. Therefore, the null hypothesis is rejected.

Question 2

The academic planner of a university thinks that at least 35% of the entire student body attends summer school.The correct set of hypotheses to test his belief is

Accepted Answer

The academic planner believes that at least 35% of the student body attends summer school. So, the null hypothesis should be that the proportion of students who attend summer school is less than or equal to 35%, and the alternative hypothesis should be that the proportion is greater than 35%.

Question 3

Read the z statistic from the normal distribution table and circle the correct answer.For a two-tailed test using α = .0160, z =

Accepted Answer

Since this is a two-tailed test, we need to divide the alpha level by 2 to get the alpha level for each tail. Thus, for an alpha of .0160, each tail has an alpha of .0080. Looking at the normal distribution table, we can find the z-score that corresponds to an area of .0080 in the tail. We see that the closest value is 2.41, so we circle choice C as the correct answer.

Question 4

A machine is designed to fill toothpaste tubes, on an average, with 5.8 ounces of toothpaste.The manufacturer does not want any underfilling or overfilling.The correct hypotheses to be tested are

Accepted Answer

The correct hypotheses to be tested should have the null hypothesis stating that the population mean is equal to the stated value (in this case, 5.8 ounces), and the alternative hypothesis should state that the population mean is not equal to the stated value. Option B is the only one that meets this requirement. The other options either do not have the correct directionality or include a non-equal alternative hypothesis without including the null hypothesis.

Question 5

In the past, 75% of the tourists who visited Chattanooga went to see Rock City.The management of Rock City recently undertook an extensive promotional campaign.They are interested in determining whether the promotional campaign actually increased the proportion of tourists visiting Rock City.The correct set of hypotheses is

Accepted Answer

The null hypothesis (H0) should state that the proportion is less than or equal to 0.75, and the alternative hypothesis (Ha) should state that the proportion is greater than 0.75, reflecting the goal of determining if the campaign increased the proportion.

Question 6

The average monthly rent for one-bedroom apartments in Chattanooga has been $700.Because of the downturn in the real estate market, it is believed that there has been a decrease in the average rental.The correct hypotheses to be tested are

Accepted Answer

The null hypothesis (H0) should reflect the status quo or no change, which is that the average rent is at least $700. The alternative hypothesis (Ha) should reflect the belief or claim being tested, which is that the average rent has decreased to less than $700.

Question 7

Read the z statistic from the normal distribution table and circle the correct answer.For a one-tailed test (upper tail) at α = .0630, z =

Accepted Answer

For a one-tailed test with α = 0.0630, you need to find the z-score that corresponds to a cumulative probability of 1 - 0.0630 = 0.9370. Looking up 0.9370 in the z-table gives a z-score of approximately 1.53.

Question 8

A two-tailed test is performed at the .05 level of significance.The p-value is determined to be .09.The null hypothesis

Accepted Answer

The p-value of .09 is greater than the significance level of .05, therefore there is not enough evidence to reject the null hypothesis.

Question 9

Read the t statistic from the t distribution table and circle the correct answer.For a one-tailed test (lower tail), using a sample size of 10, and at the 10% level of significance, t =

Accepted Answer

To find the t-value, we need to look at the row for degrees of freedom (df) 9 (since sample size is 10, df = n-1 = 10-1 = 9) in the t distribution table. Then, we look at the column for the 10% level of significance, which is 1-tailed and in the lower tail. This gives us a t-value of -1.383. Therefore, the correct answer is C.

Question 10

Read the t statistic from the t distribution table and circle the correct answer.For a one-tailed test (upper tail) with a sample size of 26 and at the .10 level, t =

Accepted Answer

For a one-tailed test (upper tail) with a sample size of 26 and at the .10 level, t = 1.316.

Question 11

The average hourly wage of computer programmers with 2 years of experience has been $21.80.Because of high demand for computer programmers, it is believed there has been a significant increase in the average hourly wage of computer programmers.To test whether or not there has been an increase, the correct hypotheses to be tested are

Accepted Answer

The null hypothesis (H0) should reflect no change or the status quo, which in this case is the average hourly wage being $21.80 or less, and the alternative hypothesis (Ha) should reflect the claim to be tested, which is an increase in the average hourly wage, hence μ > 21.80.

Question 12

Read the t statistic from the t distribution table and circle the correct answer.For a one-tailed test (upper tail), using a sample size of 18, and at the 5% level of significance, t =

Accepted Answer

For a one-tailed test (upper tail), using a sample size of 18, and at the 5% level of significance, t = 1.740.

Question 13

In a one-tailed hypothesis test (lower tail), the test statistic is determined to be -2.The p-value for this test is

Accepted Answer

To find the p-value for a one-tailed hypothesis test (lower tail), we need to find the area to the left of the test statistic in the t-distribution. Looking up the area in a t-table for a one-tailed test with  degrees of freedom (based on the sample size minus one), we get a p-value of .0228.

Question 14

A juice drink filling machine, when in perfect adjustment, fills the bottles with 12 ounces of drink on an average.Any overfilling or underfilling results in the shutdown and readjustment of the machine.To determine whether or not the machine is properly adjusted, the correct set of hypotheses is

Accepted Answer

The null hypothesis (H0) should state that the machine is properly adjusted, which means the mean fill is 12 ounces. The alternative hypothesis (Ha) should state that the machine is not properly adjusted, meaning the mean fill is not 12 ounces.

Question 15

Read the z statistic from the normal distribution table and circle the correct answer.For a one-tailed test (lower tail) using α = .1020, z =

Accepted Answer

For a one-tailed test with α = 0.1020, we look for the z-score that corresponds to the cumulative probability of 0.1020 in the lower tail. The z-score closest to this probability is -1.27.

Question 16

The average manufacturing work week in metropolitan Chattanooga was 40.1 hours last year.It is believed that the recession has led to a reduction in the average work week.To test the validity of this belief, the hypotheses are

Accepted Answer

The null hypothesis H₀: μ ≥ 40.1 states that the average work week is greater than or equal to 40.1 hours. The alternative hypothesis H_a: μ < 40.1 states that the average work week is less than 40.1 hours. This aligns with the belief that the recession has led to a reduction in the average work week. Therefore, option B is the best choice.

Question 17

Read the t statistic from the t distribution table and circle the correct answer.For a one-tailed test (lower tail) with 22 degrees of freedom at α = .05, the value of t =

Accepted Answer

For a one-tailed test with 22 degrees of freedom at α = .05, the critical t value is -1.717.

Question 18

The average life expectancy of tires produced by the Whitney Tire Company has been 40,000 miles.Management believes that due to a new production process, the life expectancy of their tires has increased.In order to test the validity of their belief, the correct set of hypotheses is

Accepted Answer

The null hypothesis (H0) should state that the average life expectancy is less than or equal to 40,000 miles, which is the current known average. The alternative hypothesis (Ha) should state that the life expectancy has increased, meaning it is greater than 40,000 miles.

Question 19

A student believes that the average grade on the final examination in statistics is at least 85.She plans on taking a sample to test her belief.The correct set of hypotheses is

Accepted Answer

The null hypothesis (H0) should represent the statement that the student wants to test against, which is that the average grade is at least 85. Therefore, H0: $\mu$ $\geq$ 85. The alternative hypothesis (Ha) is what the student would conclude if the null hypothesis is rejected, which is that the average grade is less than 85.

Question 20

In a two-tailed hypothesis test, the test statistic is determined to be z = -2.5.The p-value for this test is

Accepted Answer

The answer of In a two-tailed hypothesis test, the test...

Quiz 9: Hypothesis Tests

For a one-tailed hypothesis test (upper tail) , the p-value is computed to be .034.If the test is being conducted at the 5% level of significance, the null hypothesis