A magazine includes a report on the energy costs per year for 32-inch liquid crystal display (LCD) televisions. The article states that 14 randomly selected 32-inch LCD televisions have a sample standard deviation of $3.43. Assume the sample is taken from a normally distributed population. Construct 98% confidence intervals for (a) the population variance σ2 and (b) the population standard deviation σ. Interpret the results. (a) The confidence interval for the population variance is (Round to two decimal places as needed.)
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- A random of 15 freshmen takers obtained a mean score of 74 and a variance of 9 on a SASE. Assuming the scores to be normally distributed, construct a 95% confidence interval to estimate the variance of scores of the whole freshmen population.Suppose the retirement age in the U.S. is normally distributed with an unknown population mean and standard deviation. A random sample of 22 retirees is taken and results in a sample mean of 59 years old and sample standard deviation of 5 years.The margin of error for a 95% confidence interval estimate for the population mean using the Student's t-distribution is 2.22. Find a 95% confidence interval estimate for the population mean using the Student's t-distribution. Round the final answers to two decimal placesAn agricultural company is trying to decide which type of fertilizer to use on its crops. The company concerned with the average yield on its crops as well as the variance of their yields. In a sample of 41 different fields with using fertilizer A, the average crop yield per acre is 185 tons with a standard deviation of 35 tons. In a separate sample of 61 different fields using fertilizer B, the average crop yield is 175 tons with a standard deviation of 28 tons. When testing the hypothesis (at the 5% level of significance) that the variance of one of these yields is significantly larger than the other, what is the null and alternative hypotheses?
- The ages of registered voters in Smith County are normally distributed with a population standard deviation of 3 years and an unknown population mean. A random sample of 18 voters is taken and results in a sample mean of 55 years. Find the margin of error for a 95% confidence interval for the population mean. z0.10z0.10 z0.05z0.05 z0.025z0.025 z0.01z0.01 z0.005z0.005 1.282 1.645 1.960 2.326 2.576 You may use a calculator or the common z values above. Round the final answer to two decimal places.The table below lists weights (carats) and prices (dollars) of randomly selected diamonds. Find the (a) explained variation, (b) unexplained variation, and (c) indicated prediction interval. There is sufficient evidence o support a claim of a linear correlation, so it is reasonable to use the regression equation when making predictions. For the prediction interval, use a 95% confidence level with a diamond that weighs 0.8 carats. Weight Price 0.3 $508 a. Find the explained variation. 0.4 $1153 0.5 $1332 Round to the nearest whole number as needed.) . Find the unexplained variation. Round to the nearest whole number as needed.) c. Find the indicated prediction interval.A paint manufacturer wants to introduce a new paint on the market. The following data were obtained for drying time (minutes) when five samples of the paint were tested. 380 290 240 310 300 Assuming that the drying time is normally distributed with a variance of 400, obtain a 99% confidence interval for the true mean drying time.In the Izmir University of Economics, a professor claims that exam scores for non-accounting majors are more variable than for accounting majors. Random samples of 30 non-accounting majors and 30 accounting majors are taken from a final exam held on 2019. Test at the 5% level the null hypothesis that the two population variances are equal against the alternative that the true variance is higher for the non-accounting majors. Assume the populations are normally distributed. s = 1584.272 ny = 30 s = 400.495 Non-Accounting n = 30 Accounting To test the professor's claim, identify the null and alternative hypotheses. The null hypothesis is represented by H, and the alternative hypothesis is represented by H,. Choose the correct answer below. O A. Ho: o 2 O B. Ho: o = OD. Ho: o =0 H,: oA random of 15 freshmen takers obtained a mean score of 74 and a variance of 9 on a SASE. Assuming the scores to be normally distributed, construct a 95% confidence interval to estimate the variance of scores of the whole freshmen population.Part Variability is critical in the manufacturing of the ball bearings. Large variances in the size of the ball bearings cause bearing failure and rapid wear out. Production standards call for a maximum variance of .0001 when the bearing sizes are measured in inches. A sample of 15 bearings shows a sample standard deviation of .014. a. Compute the 90% confidence interval estimate of the variance of the ball bearings in the population. b. Use a= 0.10 to determine whether the sample indicates that the maximum acceptable variance is being exceeded. Use critical value approach. ( Note: You must state null and alternative hypotheses, compute the test statistic, Report the critical Value, and draw a conclusion.The electric cooperative needs to know the mean household usage of electricity by its non-commercial customers in kWh per day. They would like the estimate to have a maximum error of 0.14 kWh. A previous study found that for an average family the variance is 4.84 kWh and the mean is 19.1 kWh per day. If they are using a 80% level of confidence, how large of a sample is required to estimate the mean usage of electricity? Question 8 options: 45 households 1959 households 949 housholds 405 householdsGive a 99.8% confidence interval, for μ₁ −μ₂ given the following information. n₁ = 35, x₁ = 1 2.41, s₁ = 0.39 81 n₂ = 20, x₂ = 2.62, s₂ = 0.83 2 -0.21 ✓0.69 X Use Technology Rounded to 2 decimal places.A researcher decides to measure anxiety in group of bullies and a group of bystanders using a 23-item, 3 point anxiety scale. Assume scores on the anxiety scales are normally distributed and the variance among the group of bullies and bystanders are the same. A group of 30 bullies scores an average of 21.5 with a sample standard deviation of 10 on the anxiety scale. A group of 27 bystanders scored an average of 25.8 with a sample standard deviation of 8 on the anxiety scale. You do not have any presupposed assumptions whether bullies or bystanders will be more anxious so you formulate the null and alternative hypothesis based on that.SEE MORE QUESTIONSRecommended textbooks for youMATLAB: An Introduction with ApplicationsStatisticsISBN:9781119256830Author:Amos GilatPublisher:John Wiley & Sons Inc
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