A sample of 40 investment customers serviced by an account manger are found to have had an average of $23,000 in transactions during the past year, with a standard deviation of $8500. A sample of 30 customers serviced by another account manager averaged $28,000 in transactions, with a standard deviation of $11,000. Assuming th
The manufacturer of a new antidepressant claims that, among all people with depression who use the drug, the proportion of people who find relief from depression is at least 80%. A random sample of 235 patients who use this new drug is selected, and 184 of them find relief from depression. Based on these data, can we reject th
The manufacturer of a new antidepressant claims that, among all people with depression who use the drug, the proportion of people who find relief from depression is at least 80%. A random sample of 235 patients who use this new drug is selected, and 184 of them find relief from depression. Based on these data, can we reject the
Create a hypothesis test to determine if the mean number of phone calls decreased between two points in time.
From her firm's computer telephone log, an executive found that the mean length of 64 telephone calls during July was 4.48 minutes with a standard deviation of 5.87 minutes. She vowed to make an effort to reduce the length of calls. The August phone log showed 48 telephone calls whose mean was 2.396 minutes with a standard devia
Proportion problem On average an organization has received 20% positive returns on their annual request for donations, out of 220 that were mailed. This year, 18.5% positive returns out of 250 were received. The level of significance is .05. Were the returns in the second year less than the historical level.
A cereal manufacturer wants to determine if the filling machine is operating to specifications. The machine is specified to fill to a 12oz level. A sample of 100 boxes of cereal is taken from the packaging line. The mean of samples is 11.85 oz., with a standard deviation of 0.5 oz. The level of significance is 0.05.
Under what circumstances should a nonparametric test be used? Explain. What are the strengths and weaknesses of nonparametric tests? Can the outcomes of nonparametric tests be generalized to populations?
What is meant by the "normal distribution? What is its relevance in statistics? Define the concept of hypothesis testings? Give an example of when you would use one in the workplace. Explain the difference between a null and an alternative hypothesis.
Develop two-null hypothesis tests to ascertain if there are any statistical variances in the averages of bus route times and any statistical variance among the average performance of the bus drivers. Use the following information to conduct the test: The three bus routes are the treatments. The three bus drivers are t
A sample of observations is drawn from a normally distributed population. Given sample mean and variance perform a hypothesis test on the population standard deviation.
A random sample of 51 observations was selected from a normally distributed population. The sample mean was x = 88.6 , and the sample variance was s2 = 38.2. We wish to determine if there is sufficient reason to conclude that the population standard deviation is not equal to 8 at the 0.05 level of significance. Calculate the
In a two-tail test at the 0.05 level, could the residents of this city be said to be significantly different from their counterparts across the nation?
The International Coffee Association has reported the mean daily coffee consumption for U.S. residents as 1.65 cups. Assume that a sample of 38 people from a North Carolina city consumed a mean of 1.84 cups of coffee per day, with a standard deviation of 0.5 cups. In a two-tail test at the 0.05 level, could the residents of thi
For each of the following pair of null and alternative hypotheses, determine whether the pair would be appropriate for a hypothesis test. If a pair is deemed inappropriate, explain why.
For each of the following pair of null and alternative hypotheses, determine whether the pair would be appropriate for a hypothesis test. If a pair is deemed inappropriate, explain why. a. Ho: mu/10, H1: mu < 10 b. Ho: mu = 30, H1: mu ≠ 30 c. Ho: mu > 90, H1: mu <= 90 d. Ho: mu <= 75, H1:mu <= 85 e. Ho: x-bar =
1) Using the confidence interval when conducting a two-tail test for the population mean we do not reject the null hypothesis if the hypothesized value for 2) Does this sample indicate a smaller average?
1) Using the confidence interval when conducting a two-tail test for the population mean we do not reject the null hypothesis if the hypothesized value for a. is to the left of the lower confidence limit b. is to the right of the upper confidence limit c. falls between the lower and upper confidence limits d. falls in th
A sample of 25 concession stand purchases, at the October 22 matinée "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,
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 patients had heart attacks and 97 of those taking the inactive pill had heart attacks. (
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 with a standard deviation of 19.6, while the last 24 papers handed in showed a mean score of 69.3 with a standard devia
1) For a simple random sample , n= 700 and p= 0.63. At the 0.025 level, test H0: π ≤ 0.60 versus H1: π 0.60 (π this symbol represents Pi) 2) The director of admissions at a large university says that 15% of high school juniors to whom she sends university literature eventually apply for admission. IN a
During 2002, college work - study students earned a mean of $1252. Assume that a sample consisting of 45 of the work-study students at a large university was found to have earned a mean of $1277 durin
During 2002, college work - study students earned a mean of $1252. Assume that a sample consisting of 45 of the work-study students at a large university was found to have earned a mean of $1277 during the year, with a standard deviation of $210. Would a one-tail test at the 0.05 level suggest the average earnings of this univer
For each of the following statements, formulate appropriate null and alternative hypotheses, Indicate whether the appropriate test will be on-tail or two-tail, then sketch a diagram that shows the app
For each of the following statements, formulate appropriate null and alternative hypotheses, Indicate whether the appropriate test will be one-tail or two-tail, then sketch a diagram that shows the approximate location of the " rejection" region(s) for the test. a. "the average college student spends no more than $300 per seme
Use a 0.05 significance level to test the claim that the heights of female supermodels vary less than the heights of women in general. The standard deviation of heights of the population of women is 2.5 in. Listed below are the heights (in inches) of randomly selected supermodels (Taylor, Harlow, Mulder, Goff, Evangelista, Aue
The Stewart Aviation Products Company uses a new production method to manufacture aircraft altimeters. A simple random sample of 81 altimeters is tested in a pressure chamber, and the errors in altitude are recorded as positive values (for readings that are too high) or negative values (for readings that are too low). The samp
A local newspaper alleges that workers at my brother's café have an extremely stressful job. Stresses come from a combination of physical and social sources such as incessant time pressure, unruly customers like Indiana Jones, and bad salads. It gets so bad that Médecins Sans Frontières decides to step in and invest
In these two exercises, test the given claim. Identify the null hypothesis, alternative hypothesis, test statistic, P-value or critical value(s), conclusion about the null hypothesis, and final conclusion that addresses the Original claim. Use the P-value method unless your instructor specifies otherwise. Analysis of Last
Test the given claim. Identify the hypothesis, alternative hypothesis, test statistic, P-value or critical value(s), conclusion about the null hypothesis, and final conclusion that addresses the original claim. Use the P-value method unless your instructor specifies otherwise. Drug Testing of Job Applicants In 1990, 5.8% o
Survey of Workers In a survey of 703 randomly selected workers, 15.93% got their jobs through newspaper ads (based on data from Taylor Nelson Sofres Intereach). Consider a hypothesis test that uses a 0.05 significance level to test the claim that less than 20% of the workers get their jobs through newspaper ads. a. What is t
When you are using statistics to decide between two hypothesis, I believe that you have to allow for the possibility of error. You have committed a Type one error if you have rejected the hypothesis tested when it was true. A type I error occurs when one rejects the null hypothesis when it is true, and a type II error occurs whe
A coin was flipped 60 times and came up heads 38 times. At the .10 level of significance, is the coin biased toward heads? Show decision rule and calculations. (b) calculate a p-value and interpret it.
The web-based company Oh Baby! Gifts has a goal of processing 95% 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 =.025.
An auditor received 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 ave
I am having major problems identifying formulas, assigning values, & recognizing symbols. This is because I had the 1st class in 2006, and this 2nd class should have followed immediately, but the academic counselors chose to assign other classes first. Now, I remember very little, & the instructor advises that I need to be ref