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Hypothesis Testing

Hypothesis Test: Citical Value

Suppose that a small college claims majority of their students graduate within four years. A random survey of 250 alumni finds that 145 of them graduated within 4 years. Given that the pair of hypotheses that correspond to the claim are as follows: H0: p <= 0.50 H1: p > 0.50 Find the critical values for the hypothesis

Hypothesis Test

Suppose that a company claims that 67% of their employees (about 2/3) buy annual parking permits for parking at their workplace. A random survey of 120 employees finds that 62 of them have annual parking permits. Given that the pair of hypotheses that correspond to the claim are as follows: H0: p = 0.67 H1: p # 0.67 F

Hypothesis Testing for claim about average employee severance

Please see the attached Word document. Suppose that a company CEO claims that the average severance package for an employee at his company is $500,000. You decide to test his claim using a significance level of a=0.05. A sample of 55 employees yields a mean of =$485,155 with a sample standard deviation of s=$125,575. Firs

Hypothesis Test

Suppose that a small college claims that they graduate at least 500 students every semester. A random sample of 31 semesters yields a sample mean of 420 with a sample standard deviation of 65. H0: m >= 500 Ha: m < 500 Find the critical value for the hypothesis test. Assume that the significance level is a=0.02. Answe

Hypothesis Test: Critical Value

Suppose that a company claims that their mean weekly sales are $12,250. A random sample 35 weeks yields a sample mean of with a sample standard deviation of s=$1250. H0: m = 12,250 H1: m # 12,250 Find the critical values for the hypothesis test. Assume that the significance level is a=0.05. Answer: ______________

Inference of population mean: Changing electrical field from natural level slows healing Is there good evidence that changing the electrical field from its natural level slows healing?

Inference of population mean: Changing electrical field from natural level slows healing Our bodies have a natural electrical field that is known to help wounds heal. Does changing the field strength slow healing? A series of experiments with newts investigated this question. The data below are the healing rates of cuts (m

Determining Null and Alternative Hypotheses

The mean height of a certain kind of plant is 125 centimeters. Suppose we want to carry out a hypothesis test to see if the mean height when these plants are treated with a certain chemical differs from 125 . State the null hypothesis H0 and the alternative hypothesis H1 that we would use for this test.

Number of bottles and the probability of each number

Please see the attached file for full problem description. 1. Given the number of bottles (0,1,2,3,4) and the probability of each number being overfilled in one month, what is the expected number of overfilled bottles per month? E(X) = SUM(x*P(x)) 2. Given n=4 & p=.3 for a binomial experiment, the

3 Statistics Problems

1. Which hypothesis testing model would be used under each of the following conditions. Use the "model number" from my handout if you wish. By line the information given in each cell is: Level of measurement, number of groups, sample size to be taken, parameter of interest and any qualifications. [Please refer to the attachme

Hypothesis Testing: Legal Services & Sentence Satisfaction

See attached data set. Using AIU's survey responses from the AIU data set, complete the following requirements in the form of a report: Perform a two-tailed hypothesis test on both the legal services satisfaction and the sentence satisfaction variable's data using a .05 significance level. Begin by creating a null and a

Testing a null hypothesis at a .05 level of significance

Assume that it is well established that the average number of correctly recalled items from a 50 item word list is 22 words. A cognitive psychologist is interested in knowing if a new mnemonic training program will improve recall on a 50 item word list. She gives the mnemonic program to 16 students and then tests their recall

Standard deviation

An auditor reviewed 25 oral surgery insurance claims from a particular surgical office, determining that the mean out-of-pocket patient billing above the reimbursed amount was $275.66 with a standard deviation of $78.11. (a) At the 5 percent level of significance, does this sample prove a violation of the guideline that the

P-value

A coin was flipped 60 times and came up heads 38 times. (a) At the .10 level of significance, is the coin biased toward heads? Show your decision rule and calculations. (b) Calculate a p-value and interpret it.

Mean, p-value

Faced with rising fax costs, a firm issued a guideline that transmissions of 10 pages or more should be sent by 2-day mail instead. Exceptions are allowed, but they want the average to be 10 or below. The firm examined 35 randomly chosen fax transmissions during the next year, yielding a sample mean of 14.44 with a standard devi

Hypothesis Test

A manufacturer is interested in determining whether it can claim that the boxes of detergent it sells contain, on average, more than 500 grams of detergent. From past experience the manufacturer knows that the amount of detergent in the boxes is approximately normally distributed. The firm selects a random sample of 100 boxes an

Hypothesis testing: U.S. Navy example

A U.S. Navy recruiting center knows from past experience that the heights of its recruits are normally distributed with mean 68 inches. The recruiting center wants to test the claim that the average height of this year's recruits is greater than 68 inches. To do this, recruiting personnel take a random sample of 64 recruits from

Walking and weight loss

A study of employees at a large company found a negative correlation between weight and distance walked on an average day. In other words, people who walked more weighed less. Would you conclude that walking causes lower weight? Can you think of an alternate explanation for the findings? This responses should be 200 words

Performance of First Grade Students vs. National Norm

In comparing the performance of first-grade students in his district with the national norm of 100 on a widely used IQ test, the results for a random sample of his first graders lead him to retain Ho: ? = 100 (? = .01) for his population. He concludes, 'My research proves that the average first grader in our district falls right

Method process for null hypothesis

Be sure to clearly state your decision on the null hypothesis 1: 9:31: At Oxnard University, a sample of 25 senior accounting majors showed a mean cumulative GPA of 3.25 with a standard deviation of 0.10. At &#945; = .05 in a two-tailed test, does this differ significantly from 3.20 (the mean GPA for all business school sen

Hypothesis Testing of Variances: Concession Stand Purchases

A sample of 25 concession stand purchases at the October 22 matinee of Bride of Chucky showed a mean purchase of $5.29 with a standard deviation of $3.02. For the October 26 evening showing of the same movie, for a sample of 25 purchases the mean was $5.12 with a standard deviation of $2.14. The means appear to be very close, bu

Test the hypothesis that students who finish an exam first get a better grade.

To test the hypothesis that students who finish an exam first get better grades, Professor Hardtack kept track of the order in which papers were handed in. The first 25 papers showed a mean score of 77.1 with a standard deviation of 19.6, while the last 24 papers handed in showed a mean score of 69.3 with a standard deviation of

10.44 Test whether Lovastatin reduce the risk of heart attack

Does Lovastatin (a cholesterol-lowering drug) reduce the risk of heart attack? In a Texas study, researchers gave Lovastatin to 2,325 people and an inactive substitute to 2,081 people (average age 58). After 5 years, 57 of the Lovastatin group had suffered a heart attack, compared with 97 for the inactive pill. (a) State the

Hypothesis Test

The Web-based company Oh Baby! Gifts has a goal of processing 95 percent of its orders on the same day they are received. If 485 out of the next 500 orders are processed on the same day, would this prove that they are exceeding their goal, using alpha = 0.025?

Hypothesis Test

Faced with rising fax costs, a firm issued a guideline that transmissions of 10 pages or more should be sent by 2-day mail instead. Exceptions are allowed, but they want the average to be 10 or below. The firm examined 35 randomly chosen fax transmissions during the next year, yielding a sample mean of 14.44 with a standard devi

Test significance of stock returns for companies

See data file attached. During the last decade, a number of institutions dedicated to improving the quality of products and services in the United States have been formed. Many of these groups annually give awards to companies that produce high quality goods and services. An investor believes that publicly traded compan

Test Surveys of Customers for Red Lobster Restaurant

The Red Lobster Restaurant chain regularly surveys its customers. On the basis of these surveys, the management of the chain claims that 75% of its customers rate the food as excellent. A consumer testing service wants to examine the claim by asking 460 customers to rate the food. What is the probability that less than 70% of

Difference Between a Left-Tailed, Two-Tailed & Right-Tailed Test

Explain the difference between a left-tailed, two-tailed, and right-tailed test. When would you choose a two-tailed test? How might you tell the direction of the test by looking at a pair of hypothesis? How might you tell which direction (or no direction) to make the hypothesis by looking at the problem statement (research quest