For one of the tasks in a manufacturing process, the mean time for tasks completion has historically been 35.0 minutes, with a standard deviation of 2.5 minutes. Workers have recently complained that the machinery used in the task in wearing out and slowing down. In response to the complaints, plant engineers have measured the
True/False Questions 1. N comparing the means of two independent samples if the test statistic indicates a significant difference at a=.05, it will also be significant at a=.10 2. For two independent samples, the comparison of means generally utilizes the student's t distribution 3. The F tests is used to compare the va
Rental car gasoline prices per gallon were sampled at eight major airports. Date for Hertz and National car rental companies follow (USA today April 4, 2000) Airport Hertz National Boston Logan 1.55 1.56 Chicago O'Hare 1.62 1.59 Los Angeles
Participant Errors with Image Errors w/o image A 14 4 B 9 2 C 12 10 D 7 8 E
Using AIU's large database of survey responses from the AIU data set, complete the following: Perform hypothesis testing on one variable's data. (Choose either the intrinsic or extrinsic column.) Perform a t-test by formulating a null and an alternative statement, choosing an acceptable significance value, determining the ap
Group A: 26, 22,24,22,21,21,26,27,21,23,19 Group B: 5,4,5,7,9,7,9,10,9,6,5 Please do an independent sample t test by hand.
An outbreak of food-borne sickness was attributed to Salmonella enteritidis. It determined that the source of the illness was spinach. Nine production runs are sampled from the spinach processing company the spinach to determine the level of Salmonella enteritidis. Levels in MPN/g are as follows: .793 .519 .392 .419 .5
A. Based on this data can the college conclude that the students in the new program performed better than the rest of the class> A one-tailed test is used equalling .05 b. Can the college conclude that the students in the new program are significantly different from the rest of the freshman class? A two-tailed test is used
Please see attached for fully formatted question. 2. Time to complete complex math problems while listening to music was investigated using 16 high school students. Students were matched on their math GPA, then randomly assigned to either the Country Western music group or the Classical music group. a. Conduct the appro
The following table shows the results after four weeks (number of pounds lost). Drug Placebo 9 8 5 6 11 2 8 3 6 5 3 6 14 2 You want to prove that the drug is effective with α=.05. Calculate the following 1) Mean and standard deviation for each sample. 2) Since i
A vinyl siding company claims that the mean time to install siding on a medium-size house is at most 20 hours with a standard deviation of 3.7 hours. A random sample of 40 houses sided in the last three years has a mean installation time of 20.8 hours. At the 0.05 significance level, can a claim be made that it takes longer on a
The number of degrees of freedom associated with the t test, when the data are gathered from a matched pairs experiment with 13 pairs, is: When the necessary conditions are met, a two-tail test is being conducted to test the difference between two population proportions. If the value of the test statistic z is 2.05, then
Chrysler Corp. is responding to an advertisement by Toyota, which claims that its compact version gets much better gasoline mileage for in-city driving than any U.S. made car. Below are the results of surveys conducted to test the claim. Perform the appropriate test at the 0.01 significance level. Do you reject or fail to reject
An industrial plant wants to determine which of two types of fuel, electric or gas, is more cost efficient (measured in cost per unit of energy). Independent random samples were taken of plants using electricity and plants using gas. These samples consisted of 14 plants using electricity, which had a mean cost per unit of $49.
An educator is considering two different videotapes for use in a half-day session designed to introduce students to the basics of economics. Students have been randomly assigned to two groups, and they all take the same written examination after viewing the videotape. The scores are summarized here. Assuming normal populations w
Perform the five-step hypothesis test on sales data to determine if there is a difference in the mean selling price of the homes with a pool and homes without a pool?
Please see attachment For a sample of 12 items from a normally distributed population for which the standard deviation is σ= 17.0 the sample mean is 230.8. At the 0.05 level of significance, test H0:   220 versus H1:  > 220. Determine and interpret the p-value for the test.
The International Council of Shopping Centers reports that the average teenager spends $39 during a shopping trip to the mall. The promotions director of a local mall has used a variety of strategies to attract area teens to his mall, including live bands and "teen-appreciation days" that feature special bargains for this age gr
Is the water on your airline flight safe to drink? It is not feasible to analyze the water on every flight, so sampling is necessary. In August and September 2004 the EPA found bacterial contamination in water samples from the lavatories and gallery water taps on 20 of 158 randomly selected U.S. flights. Alarmed by the data, the
In this exercise, assume that a simple random sample has been selected from a normally distributed population. Find the null and alternative hypotheses, test statistic, P-value (or range of P-values), critical value(s), and state the final conclusion. Claim: The mean life span of desktop PCs is less than 7 years.
Use a t-test to investigate the claim and assume that the population is normally distributed: A large university says the mean number of classroom hours per week for full-time faculty is more than 9. A random sample of the number of classroom hours for full-time faculty for one week is listed. At alpha = 0.05 , test the univer
Are women's feet getting bigger? Retailers in the last 20 years have had to increase their stock of larger sizes. Wal-Mart Stores, Inc., and Payless ShoeSource, Inc., have been aggressive in stocking larger sizes, and Nordstrom's reports that its larger sizes typically sell out first. Assuming equal variances, at α = .025,
Dr. Justin Case wants to explore whether or not students perform better if they cram for a test (massed practice) or if they space their studying over weeks (distributed practice). The massed practice group studies for 8 hours the night before a quiz; the distributed practice group also studies for 8 hours, but does it in 2-hour
A medical researcher is interested in whether patients' left arms or right arms are longer. If 14 patients participate in this study ( so that n left arms and n left arms are measured), how many degrees of freedom should the researcher use in her t-test critical value? A)26 B)27 C)14 D)13.
A data set includes the heights of parents of 20 males. If the difference in height for each set of parents is found by subtracting the mother's height from the father's height, the result is a list of 20 values with a mean of 4.4 inches and a standard deviation of 4.2 inches. Use a 0.01 significance level to test the claim th
Try out some of your own ideas for analyzing this data. Use one of the following techniques: regression line and equation; correlation one-sample t-test one-sample t confidence interval matched-pairs t-test two-sample t-test two-sample t confidence interval F-test for variances ANOVA one-sample z test for proportions
Suppose that a one-tailed t-test is being applied to find out if the population mean is less than $212. The level of significance selected is 0.01 and 26 accounts are sampled. What is the critical value? a. -2.580 b. -2.485 c. -1.960 d. -2.479
Please see attached 42. The president of the American Insurance Institute wants to compare the yearly costs of auto insurance offered by two leading companies. He selects a sample of 15 families, some with only a single insured driver, others with several teenage drivers, and pays each family a stipend to contact the two c
Students at the University of Arkansas randomly selected 217 student cars and found that they had ages with a mean of 7.89 years and a standard deviation of 3.67 years. They also randomly selected 152 faculty cars and found that they had ages with a mean of 5.99 years and a standard deviation of 3.65 years. Use a 0.01 significan
I need help with this one. Please use the intrinsic column if possible so I can compare with the work I have already done to find where I ran into trouble, thank you. Using the data set provided: Perform hypothesis testing on one variable's data. (Choose either the intrinsic or extrinsic column.) Perform a t-test by formulati