The pooled variance estimator (sp2) (round off to three decimal places) is:
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A: Given Group 1 n1=26 Xbar1=33 S1=6 Group 2 n2=25 Xbar2=36 S2=2
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A: The pooled variance is, sp2=n1-1s12+n2-1s22n1+n2-2=35-110.52+35-110.2235+35-2=7285.8668=107.145 The…
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A 30 month study is conducted to determine the difference in rates of accidents per month between two departments in an assembly plant. If a sample of 12 from the first department averaged 12.3 accidents per month with a standard deviation of 3.5, and a sample of 9 from the second department averaged 7.6 accidents per month with standard deviation of 3.4, find: The pooled variance estimator (sp2) (round off to three decimal places) is:
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- In a recent study, the strengths of a plywood and oriental strand brand (OSB) were compared. Independent random samples of each type of wood were obtained, and the dry density of each piece (in g/m ) was measured. Assume that populations are normal and the variances are equal. The summary statistics are given in the following table: Plywood n, =12 X, =581.8 X, =605.2 s =5.56 OSB n =15 s, =7.23 a. Find a 99% confidence interval for the difference in population mean dry densities. b. Interpret the interval found in part a. c. Do the data indicate that the true mean dry density of plywood is significantly less than the true mean dry density of OSB? Us a = 0.05. (i) State the null and alternative hypotheses. (ii) Calculate the value of the test statistic. (iii) Rejection region. (iv) Conclusion. (vi) What assumption are necessary for the test in part e to be valid?A researcher randomly sampled 100 graduates of an MBA program and recorded data concerning their starting salaries. Of primary interest to the researcher was the effect of gender on starting salaries. The summary results are given below: Male MBA Graduates: Sample mean = $85500, Sample standard deviation = 10000, Sample size = 50 Female MBA Graduates: Sample mean = $78000, Sample standard deviation = 8000, Sample size = 50 Assuming that the populations are normally distributed and the population variances from both populations are equal, is there evidence that the average starting salary of the male MBA graduates is higher than the average starting salary of the female MBA graduates? Use a 0.05 level of significance. (a) State the null and alternative hypothesis for this problem. (b) What is the value of the pooled-variance tSTAT test statistic for this problem? (c) Using the level of…A study was undertaken to compare the average high-density lipoprotein (HDL) levels of normal and obese adults in a certain community. HDL levels of a random sample of adults from this community were measured (in milligrams per deciliter or mg/dL) and presented below. Assume that the HDL levels of both the normal and obese adults follow the normal distribution with unknown but equal population variances. Is there a significant difference between the average HDL levels of normal and obese adults? Use a 5% level of significance.
- In the African savannah, elephants like to eat very young trees. Imaginethat, in a section of the savannah, the mean height of young trees is 30.0 cm with a variance of 25.0 cm2. Assume that young tree height is normally distributed. a. What percentage of young trees would be eaten if elephants eat alltrees shorter than 34.0 cm? b. In a section of the savannah, there are many young trees. If wetake a random sample of 36 trees what is the probability that the meanheight of our sample is between 28.0 and 33.0 cm?For a standardized psychology examination, the scores have a mean of 500 and a variance of 9475. It is hypothesized that the variance, o, of scores for psychology majors on this exam is lower than 9475. A random sample of 26 exams completed by psychology majors had a mean of 509 and a variance of 3987. Assuming that scores among psychology majors on this exam are approximately normally distributed, may we conclude, at the 0.01 level of significance, that the hypothesis is correct? Perform a one-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places and round your answers as specified below. (If necessary, consult a list of formulas.) (a) State the null hypothesis H, and the alternative hypothesis H,. H, :0 H :0 (b) Determine the type of test statistic to use. OSO (Choose one) ▼ (c) Find the value of the test statistic. (Round to three or more decimal places.) OA school administrator wants to see if there is a difference in the number of students per class for Portland Public School district (group 1) compared to the Beaverton School district (group 2). Assume the populations are normally distributed with unequal variances. A random sample of 28 Portland classes found a mean of 36 students per class with a standard deviation of 5. A random sample of 27 Beaverton classes found a mean of 35 students per class with a standard deviation of 6. Find a 90% confidence interval in the difference of the means. Use technology to find the critical value using df = 50.6214 and round answers to 4 decimal places.A simple random sample of 100 water meters within a community is monitored to estimate the average daily water consumption per household over a specified dry spell. The mean and variance for this sample are 12 and 1250, respectively. If we assume that there are N= 1000 houscholds within the community, and the maximum and minimum water consumption values per household are 23 and 3 respectively, estimate the true mean of daily water consumption.if a researcher undertook an experiment to evaluate the efficacy of a memory enhancement technique among a cohort of 15 college students. The memory recall abilities of each student were assessed both before and after they underwent training in the memory technique. The observed average increase in memory recall scores following the training was 5 points. The sample variance of the differences within the entire sample was denoted as 8. Does this research question aim to ascertain whether there is a statistically significant elevation in memory recall scores after the implementation of the memory improvement training? To address this question, a one-tailed test with a significance level of (alpha = 0.01) is employed.A basketball coach believes that the variance of the heights of adult male basketball players is different from the variance of heights for the general population of men. The sample variance of heights, measured in inches, for a random sample of 19 basketball players is 14.22. The sample variance for a random sample of 18 other men is 34.49. Assume that both population distributions are approximately normal and test the coach's claim using a 0.10 level of significance. Does the evidence support the coach's claim? Let male basketball players be Population 1 and men in general be Population 2. Step 3 of 3: Draw a conclusion and interpret the decision.An independent-measures study produces sample means of M1 = 20 and M2 = 17. If both samples have n = 18 scores and Cohen's d= 0.50, what is the value for the pooled variance?An analysis of variances produces dftotal = 35 and dfwithin = 32. For this analysis, what is dfbetween?The accounting department analyzes the variance of the weekly unit costs reported by two production departments. A sample of 16 cost reports for each of the two departments shows cost variances of 2.4 and 5.6, respectively. Is this sample sufficient to conclude that the two production departments differ in terms of unit cost variance? Use a = 0.10. You may need to use the appropriate technology to answer this question. State the null and alternative hypotheses. 2. Ho: a H: 01 Ho 2 2 +02. = 2 02, Ha: 01 >『っ 2 Ho: 01 Find the value of the test statistic. (Round your answer to two decimal places.) Find the p-value. (Round your answer to four decimal places. Remember: When using WebAssign technology to find p-values, use the entire test statistic (not the rounded answer from the previous question.)) p-value = State your conclusion. Do not reject Ho. We can conclude that there is a difference between the population variances. Do not reject Hg. We cannot conclude that there is a difference…SEE MORE QUESTIONSRecommended textbooks for youMATLAB: An Introduction with ApplicationsStatisticsISBN:9781119256830Author:Amos GilatPublisher:John Wiley & Sons Inc
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