Managerial statistics

Chapter 10 1. Due to high production-changeover time and cost, a director of manufacturing must convince management that a proposed manufacturing method reduces costs before the new method can be implemented. The current production method operates with a mean cost of $250 per hour. A research study will measure the cost of the new method over a sample production period. Required 1 . Develop the null and alternative hypotheses ii. What would you conclude when Ho cannot be rejected? iii. What would you conclude when Ho can be rejected? 2. A sample of 36 observations is selected form a normal population. The sample mean is 21, and the population standard deviation is 5. Conduct the following test of hypothesis using the 0.05 significance level. Ho: H - 20 Ha: H > 20 Required a. Is this a one or two-tailed test? b. What is the decision rule? c. What is the value of the test statistic? d. What is your decision regarding Ho? e. What is the p-value? Interpret it. f. What is the rejection rule using the critical value approach? 3. Find the following chi-square distribution values a. Xo.os with df = 5 b. Xo.95 with df = 18 C. Xo.25 with df = 15 d. X3.975 with df = 20 4. A sample of 20 items provides a sample standard deviation of 5 Required a. Compute the 90% confidence interval estimate of the population variance b. Compute the 95% confidence interval estimate of the population variance c. Compute the 95% confidence interval estimate of the population standard deviation 1