Volunteers who had developed a cold within the previous 24 hours were randomized to take either zinc or placebo lozenges every 2 to 3 hours until their cold symptoms were gone.Twenty-five participants took zinc lozenges, and 23 participants took placebo lozenges. The mean overall duration of symptoms for the zinc lozenge group was 3.5 days, and the standarddeviation of overall duration of symptoms was 1.2 days. For the placebo group, the mean overall duration of symptoms was 8.2 days, and the standard deviation was 1.8 days.(a) Calculate a 95% confidence interval for the mean overall duration of symptoms if everyone in the population were to take the zinc lozenges. (Round your answers to twodecimal places.)X daysX to(b) Calculate a 95% confidence interval for the mean overall duration of symptoms if everyone in the population were to take the placebo lozenges. (Round your answers to twodecimal places.)daysto

Answered: Volunteers who had developed a cold…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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A children’s clothing company sells hand-smocked dresses for girls. The length of one particular size of dress is designed to be 3939 inches. The company regularly tests the lengths of the garments to ensure quality control, and if the mean length is found to be significantly longer or shorter than 3939 inches, the machines must be adjusted. The most recent simple random sample of 2929 dresses had a mean length of 36.8936.89 inches with a standard deviation of 7.567.56 inches. Assume that the population distribution is approximately normal. Perform a hypothesis test on the accuracy of the machines at the 0.0250.025 level of significance. Step 2 of 3 : Compute the value of the test statistic. Round your answer to three decimal places. step 3of 3 : Conclusion - Reject the null hypothesis/ fail to reject ...insufficient/sufficient
A simple random sample of 25 filtered 100 mm cigarettes is obtained, and the tar content of each cigarette is measured. The sample has a mean of 19.8 mg and a standard deviation of 3.18 mg. Use a 0.05 significance level to test the claim that the mean tar content of filtered 100 mm cigarettes is less than 21.1 mg, which is the mean for unfiltered king size cigarettes. What do the results suggest, if anything, about the effectiveness of the filters?
The manager of the shipping department of a mail-order operation located in New York advertises that the length of time it takes for customers in California to receive their orders is 8 days. However, the office has been receiving complaints from customers in California stating that orders do not arrive in time advertised. To learn more about this potential problem, the manager chose a random sample of 15 orders. The sample mean of delivery times was 12.25 days. The sample standard deviation was 3.67 days.The average time it takes for all California customers to receive their orders is to be estimated with a 99% confidence interval. a. The ? − or ? −value that should be used to construct this interval is b. The margin of error is equal to
The average weight of new-born kittens is 3.5 ounces. A breeder suspects one of her cats, Stella, produces extra small kittens. The breeder’s suspicions arise from the weights of Stella’s most recent litter of kittens: {3.1, 3.3, 3.0, 3.7, 2.9, 2.9}. Note that the sample mean is 3.15 oz. Assume that the standard deviation of the weight of all Stella’s new-born kittens is 0.3 oz. a. In order for the above inferences to be valid, it is necessary for us to assume the sample is randomly selected from a normally distributed population. Are there any indications that either of these assumptions are violated? Explain. Hint: To check one of these assumptions, you will find it helpful to construct a histogram or a stem-and-leaf display.
One group of 50 students took a distance learning class, while another group of 25 took the same course in a traditional face-to-face classroom. Both group were given the same mid-term test. The average score of the distance learning group was 52.0 with a standard deviation of 15.4. The average score for the group who took the course in the traditional format was 58.0 with a standard deviation of 18.0. At a significance level of 0.1, can it be concluded that there is a difference in average score of students between the distance learning and face-to face instruction formats? Determine which of the following formulations of the hypotheses is appropriate and enter the corresponding number in the answer text box. Note: Index "v" refers to the population of students taking distance learning classes (virtual mode) and index "" refers to the population of students taking face-to-face classes (traditional mode). For example if you believe formulation number 4 below is the most appropriate…
Bone mineral density (BMD) is a measure of bone strength. Studies show that BMD declines after age 45. The impact of exercise may increase BMD. A random sample of 59 women between the ages of 41 and 45 with no major health problems were studied. The women were classified into one of two groups based upon their level of exercise activity: walking women and sedentary women. The 39 women who walked regularly had a mean BMD of 5.96 with a standard deviation of 1.22. The 20 women who are sedentary had a mean BMD of 4.41 with a standard deviation of 1.02. Which of the following inference procedures could be used to estimate the difference in the mean BMD for these two types of women
A children's clothing company sells hand-smocked dresses for girls. The length of one particular size of dress is designed to be 29 inches. The company regularly tests the lengths of the garments to ensure quality control, and if the mean length is found to be significantly longer or shorter than 29 inches, the machines must be adjusted. The most recent simple random sample of 18 dresses had a mean length of 33.46 inches with a standard deviation of 5.89 inches. Assume that the population distribution is approximately normal. Perform a hypothesis test on the accuracy of the machines at the 0.025 level of significance. Step 3 of 3: Draw a conclusion and interpret the decision. Answer 田 Tables 回 Keypad Keyboard Shortcuts We fail to reject the null hypothesis and conclude that there is insufficient evidence at a 0.025 level of significance that the mean length of the particular size of dress is found to be significantly longer or shorter than 29 inches and the machines must be adjusted.…
A researcher selected a sample of 156 former student leaders from a list of graduates of a large university. She discovered that it had taken an average of 4.97 years for the graduates to finish their degrees, with a standard deviation of 1.23. The average for the entire student body is 4.56 years. Is the difference statistically significant? Alpha = 0.05; two-tailed test.
Is the strep virus getting harder or easier to heal? Pediatricians are interested in studying the average length of time patients with strep are running fever while on antibiotics. In previous years, the average length of time patients ran fever with strep while on antibiotics was 1.8 days. A random sample of forty-six patients with strep ran fever while on antibiotics for an average of 2.3 days with standard deviation 1.2. at the 5% significance level, can pediatricians conclude that the average amount of time patients with strep run fever while on antibiotics has changed? Assume the random variable has a normal distribution. a. Find the rejection region b. Find the p-value c. State the Decision and the Conclusion in terms of the problem d. If Ho is rejected, find and interpret the appropriate confidence interval.
A study was conducted in which mice that had a dim light on at night (rather than complete darkness) ate most of their calories when they should have been resting. These mice gained a significant amount of weight, despite eating the same number of calories as mice kept in total darkness. The time of eating seemed to have a significant effect. There were 10 mice in the group with dim light at night and they gained an average of 7.9 g with a standard deviation of 3.0. We see in Figure 1 that the data are not heavily skewed and do not have extreme outliers. 00 O O 2 4 8 10 12 14 BM Gain Figure 1 Body mass gain (in grams) for mice with a night light Use the t-distribution to find a 90% confidence interval for weight gain. Round your answers to two decimal places. The 90% confidence interval is i to i !
A randomized controlled trial is run to evaluate the effectiveness of a new drug for asthma in children. A total of 250 children are randomized to either the new drug or a placebo (125 per group). The mean age of children assigned to the new drug is 12.4 with a standard deviation of 3.6 years. The mean age of children assigned to the placebo is 13.0 with a standard deviation of 4.0 years. Suppose that there are 63 boys assigned to the new drug group and 58 boys assigned to the placebo group. Is there a statistically significant difference in the proportions of boys assigned to the treatments? Run the appropriate test at a 5% level of significance.
In a test of the effectiveness of garlic for lowering cholesterol, 4949 subjects were treated with raw garlic. Cholesterol levels were measured before and after the treatment. The changes (before minus after) in their levels of LDL cholesterol (in mg/dL) have a mean of 0.40.4 and a standard deviation of 23.823.8. Use a 0.010.01 significance level to test the claim that with garlic treatment, the mean change in LDL cholesterol is greater than 00. What do the results suggest about the effectiveness of the garlic treatment? Assume that a simple random sample has been selected. Identify the null and alternative hypotheses, test statistic, P-value, and state the final conclusion that addresses the original claim. Determine the test statistic. nothing (Round to two decimal places as needed.)

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