Exam 9: Hypothesis Tests

Exhibit 9-7 A random sample of 16 statistics examinations from a large population was taken.The average score in the sample was 78.6 with a variance of 64.We are interested in determining whether the average grade of the population is significantly more than 75.Assume the distribution of the population of grades is normal. -Refer to Exhibit 9-7.The p-value is between

Exhibit 9-4 The manager of a grocery store has taken a random sample of 100 customers.The average length of time it took the customers in the sample to check out was 3.1 minutes with a standard deviation of 0.5 minutes.We want to test to determine whether or not the mean waiting time of all customers is significantly more than 3 minutes. -Refer to Exhibit 9-4.The p-value is between

It is said that more males register to vote in a national election than females.A research organization selected a random sample of 300 registered voters and reported that 165 of the registered voters were male. a.Formulate the hypotheses for this problem. b.Compute the standard error of. c.Compute the test statistic. d.Using the p-value approach,can you conclude that more males registered to vote than females? Let $\alpha$ = .05.

If a hypothesis test leads to the rejection of the null hypothesis,

Nancy believes that the average running time of movies is equal to 140 minutes.A sample of 4 movies was taken and the following running times were obtained.Assume the population of the running times is normally distributed. a.Compute the sample mean and the standard deviation. b.State the null and alternative hypotheses. c.Using the critical value approach,test the hypotheses at the 10% level of significance. d.Using the p-value approach,test the hypotheses at the 10% level of significance.

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

If a hypothesis is not rejected at the 5% level of significance,it

Exhibit 9-3 -Refer to Exhibit 9-3.The test statistic is

Exhibit 9-2 -Refer to Exhibit 9-2.The test statistic equals

Exhibit 9-5 A random sample of 100 people was taken.Eighty-five of the people in the sample favored Candidate A.We are interested in determining whether or not the proportion of the population in favor of Candidate A is significantly more than 80%. -Refer to Exhibit 9-5.At 95% confidence,it can be concluded that the proportion of the population in favor of candidate A

The p-value ranges between

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

Consider the following hypotheses test. H_o: $\mu$ $\ge$ 80 H_a: $\mu$ < 80 A sample of 121 provided a sample mean of 77.3.The population standard deviation is known to be 16.5. a.Compute the value of the test statistic. b.Determine the p-value;and at 93.7% confidence,test the above hypotheses. c.Using the critical value approach at 93.7% confidence,test the hypotheses.

What type of error occurs if you fail to reject H₀ when,in fact,it is not true?

Exhibit 9-2 -Refer to Exhibit 9-2.The p-value is between

Exhibit 9-3 -Refer to Exhibit 9-3.The p-value is between

An assumption made about the value of a population parameter is called a

The Department of Economic and Community Development (DECD)reported that in 2009 the average number of new jobs created per county was 450.The department also provided the following information regarding a sample of 5 counties in 2010. a.Compute the sample average and the standard deviation for 2010. b.We want to determine whether there has been a significant decrease in the average number of jobs created.Provide the null and the alternative hypotheses. c.Compute the test statistic. d.Compute the p-value;and at 95% confidence,test the hypotheses.Assume the population is normally distributed.

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

Exhibit 9-6 A random sample of 16 students selected from the student body of a large university had an average age of 25 years and a standard deviation of 2 years.We want to determine if the average age of all the students at the university is significantly more than 24.Assume the distribution of the population of ages is normal. -Refer to Exhibit 9-6.The test statistic is