A time study of a large production facility was undertaken to determine the mean time required to assemble a cell phone. A random sample of the times to assemble 50 cell phones was recorded. An analysis of the assembly times reveals that they are normally distributed with a standard deviation of 1.3 minutes. Estimate with 95% confidence the mean assembly time for all cell phones. What do your results tell you about the assembly times?
Answer to relevant QuestionsThe image of the Japanese manager is that of a workaholic with little or no leisure time. In a survey, a random sample of 250 Japanese middle managers was asked how many hours per week they spent in leisure activities (e.g., ...Review Exercise 10.41. Describe what happens to the sample size whena. The population standard deviation increases.b. The confidence level increases.c. The bound on the error of estimation increases.Review Exercises 10.48 and 10.49. Describe what happens to the confidence interval estimate whena. The standard deviation is equal to the value used to determine the sample size.b. The standard deviation is smaller than the ...a. A random sample of 100 observations was randomly drawn from a population with a standard deviation of 5. The sample mean was calculated as x̄ = 400. Estimate the population mean with 99% confidence.b. Repeat part (a) ...H0: µ = 70H1: µ > 70σ = 20, n = 100, x̄ = 80, α = .01Calculate the value of the test statistic, set up the rejection region, determine the p-value, interpret the result, and draw the sampling distribution.
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