9A A personnel researcher has designed a questionnaire and she would like to estimate the average time to complete the questionnaire. Suppose she samples 100 employees and finds that the mean time to take the test is 27 minutes with a standard deviation of 4 minutes. Construct a 90% confidence interval for the mean time to complete the questionnaire. Also, write a short explanation about the findings to the human resources director of your company summarizing the results. – Use Excel for this analysis.

9B. For the problem in part A, the human resources director wants to know whether these is sufficient sample evidence to conclude that the average time to complete the questionnaire is not 27 minutes. Set up the hypotheses (in statistical terms) and, based only on the confidence interval you have constructed in part A, what would you conclude regarding the hypotheses?

H0 :

H1 :

In a study conducted to investigate browsing activity by shoppers, each shopper was initially classified as a nonbrowser, light browser, or heavy browser. For each shopper, the study obtained a measure to determine how comfortable the shopper was in a store. Higher scores indicated greater comfort. Suppose the following data were collected.

a. Use a= .05 to test for a difference among mean comfort scores for the three types of browsers.

Compute the values identified below (to 2 decimals, if necessary).

Calculate the value of the test statistic (to 2 decimals, if necessary).

b. Use Fisher's LSD procedure to compare the comfort levels of nonbrowsers and light browsers. Use a= .05 .

Compute the LSD critical value (to 2 decimals).

A psychologist believes that students’ test scores will be affected if they have too much caffeine before taking an exam. To examine this, she has a sample of n = 15 students drink five cups of coffee before taking an exam. She uses an exam that has a population mean of µ = 72 and a population standard deviation s = 3. The mean test score for the sample of 15 students who drank five cups of coffee before taking the exam was M = 69. Do a t-test using a = .01 a. Is this a one-tailed test or a two-tailed test? (circle one) b. What is the research hypothesis, H1? c. What is the null hypothesis, H0? d. Calculate the degrees of freedom (df) for this problem. e. From the t-distribution table (B.2), what is the critical value of tcrit for a = .01? f. Calculate the mean of the distribution of sample means, µM g. Calculate the standard error of the mean, sM h. Calculate the t-score of the sample mean. i. Sketch the distribution of sample means. Indicate where the sample mean is, where the critical value of t is, and the area under the tail of the curve. j. Can you reject the null hypothesis, H0? YES or NO (circle one) k. Can you accept the research hypothesis, H1? YES or NO (circle one)

The output of a chemical process is monitored by taking a sample of 20 vials to determine the level of impurities. The desired mean level of impurities is 0.048 grains per vial. If the mean level of impurities in the sample is too high, the process will be stopped and purged; if the sample mean is too low, the process will be stopped and the values will be readjusted. Otherwise, the process will continue.
a)  Sample results provide sample mean to be equal to 0.057 gram with sample standard deviation equal to 0.018. At a significance level of 0.01, should the process be stopped? If so, what type of remedial action will be required?
b)  Assume that the mean level of impurities is within tolerable limits. If the maximum tolerable variability of the process is 0.0002, do the sample results verify the suspicion that the maximum tolerable variability has been exceeded? Use a 5% level of significance.

Why are sampling distributions important to the study of inferential statistics? In your answer, demonstrate your understanding by providing an example of a sampling distribution from an area such as business, sports, medicine, social science, or another area with which you are familiar. Remember to cite your resources and use your own words in your explanation.

Of the travelers arriving at a small airport, 50% fly on major airlines, 20% fly on privately owned planes, and the remainder fly on commercially owned planes not belonging to a major airline. Of those traveling on major airlines, 40% are traveling for business reasons, whereas 60% of those arriving on private planes and 90% of those arriving on other commercially owned planes are traveling for business reasons. Suppose that we randomly select one person arriving at this airport.

(a) What is the probability that the person is traveling on business?

(b) What is the probability that the person is traveling for business on a privately owned plane?

(c) What is the probability that the person arrived on a privately owned plane, given that the person is traveling for business reasons? (Round your answers to four decimal places.)

(d) What is the probability that the person is traveling on business, given that the person is flying on a commercially owned plane?

In an attitude test, 55 out of 120 persons of Community 1 and 115 persons out of 400 of Community 2 answered “Yes” to a certain question. Do these two communities differ fundamentally in their attitudes on this question?

There are twenty stores for a grocery chain in the Mid-Atlantic region. The regional executive wants to visit five of the twenty stores. She asks her assistant to choose five stores and arrange the visit schedule. (Show all work. Just the answer, without supporting work, will receive no credit). (a) Does the order matter in the scheduling? (b) Based on your answer to part (a), should you use permutation or combination to find the different schedules that the assistant may arrange? (c) How many different schedules can the assistant recommend?

Here is a bivariate data set.

Find the correlation coefficient and report it accurate to three decimal places.
r =

The accompanying data file shows the square footage and associated property taxes for 20 homes in an affluent suburb 30 miles outside of New York City. Estimate a home’s property taxes as a linear function of its square footage. At the 5% significance level, is square footage significant in explaining property taxes? Show the relevant steps of the test.

Please use Minitab and explain the various steps involved.

1. Young children in the U.S. are exposed to an average of 4 hours of television per day, which can adversely impact a child’s well-being. You are working in a research lab that hypothesizes that children in low income households are exposed to more than 4 hours of television. In order to test this hypothesis, you collected data on a random sample of 75 children from low income households. You found a sample mean television exposure time of 4.5 hours. Based on a previous study, you are willing to assume a population standard deviation of 0.5 hours. a. Using this information, test your hypothesis using the critical value approach; assume a significance level of 10%. b. Calculate the p-value associated with your test statistic. Using the p-value approach, what is your hypothesis test conclusion?

The population average cholesterol content of a certain brand of egg is 215 milligrams, and the standard deviation is 15 milligrams. Assume the variable is normally distributed.

(a) Find the probability the cholesterol content for a single egg is between 210 and 220.

(b) Find the probability the average cholesterol contentfor 25 eggs is between 210 and 220.

(c) Find the third quartile for the average cholesterol content for 25 eggs.

(d) If we are told the average for 25 eggs is less than 220mg, what is the probability the average is less than210 mg?

State the likely relative positions of the mean, median, and mode for the following distributions:

Family income in large city

Scores on a very easy exam

Heights of a large group of 25-year old males

The number of classes skipped during the year for a large group of undergraduate

Terri Vogel, an amateur motorcycle racer, averages 129.71 seconds per 2.5 mile lap (in a seven-lap race) with a standard deviation of 2.28 seconds. The distribution of her race times is normally distributed. We are interested in one of her randomly selected laps.

• Part (a)

  In words, define the random variable X.

  the time (in seconds) per lapthe time (in seconds) per race    the distance (in miles) of each racethe distance (in miles) of each lap

• Part (b)

  Give the distribution of X.
  X ~

• Part (c)

  Find the percent of her laps that are completed in less than 135 seconds. (Round your answer to two decimal places.)
  

• Part (d)

  The fastest 2% of her laps are under how many seconds? (Round your answer to two decimal places.)
  sec

• Part (e)

  Enter your answers to two decimal places.
  
  The middle 80% of her lap times are from  seconds to  seconds.

In a randomized controlled​ trial, insecticide-treated bednets were tested as a way to reduce malaria. Among 322 infants using​ bednets, 13 developed malaria. Among

276 infants not using​ bednets, 29 developed malaria. Use a 0.05 significance level to test the claim that the incidence of malaria is lower for infants using bednets. Do the bednets appear to be​ effective? Conduct the hypothesis test by using the results from the given display.

please show me how to do on ti-84

Difference=​p(1)minus−​p(2)

Estimate for​ difference: - 0.0646998

95% upper bound for​ difference: - 0.02261687

Test for difference=0 ​(vs <​ 0): Z=- 3.09  

​P-Value=0.001