DSCI 3710 Exam1AMay2010Key

# DSCI 3710 Exam1AMay2010Key - COURSE: DSCI 3710 Exam 1...

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Use the information given in the following paragraph to answer next three questions. A lumber company is making 2x4s that are 12 feet long. These 2x4s are being used to make prefabricated homes. If the 2x4s are too long they must be trimmed and if too short they cannot be used. A sample of 230 2x4s is made, and it is found that they averaged 11.9 feet with a standard deviation of 0.04 feet. Is there evidence, at the 0.01significance level, that the 2x4s are either too long or too short? 1. What are the null hypothesis and alternative hypothesis for this test? A. Ho: μ = 11.9 Ha: μ 11.9 B. Ho: μ 11.9 Ha: μ < 11.6 C. Ho: μ = 12 Ha: μ 12* D. Ho: μ > 12 Ha: μ 11.8 E. Ho: μ = 12 Ha: μ < 11.8 2. What is the absolute critical value of the test statistic? A. 0.12 B. 1.96 C. 2.33 D. 3.69 E. 2.57* 3. Assuming the calculated value of the test statistic is -1.53 , what are the decision and conclusion of the test? A. Fail to reject the null hypothesis, conclude there is overwhelming evidence the 2x4s are not too long or too short. B. Fail to reject the null hypothesis, conclude there is insufficient evidence the 2x4s are too long or too short* C. Reject the null hypothesis, conclude there is evidence the 2x4s are too long or too short. D. Fail to reject the null hypothesis, conclude there is evidence the 2x4s are too long or too short. E. Reject the null hypothesis, conclude there is insufficient evidence the 2x4s are too long or too short.
Use the information given below to answer the next question. The production manager in a chemical plant knows that the time for a certain product line to become stable after being stopped for machine adjustments is normally distributed. He uses a sample of 15 stoppages to determine a 90% confidence interval for the average warm-up period to be 7.3 to 9.7 minutes. The firm = s cost accountant would like to answer the following question:

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## This note was uploaded on 03/07/2011 for the course DSCI 3710 taught by Professor Dr.jay during the Spring '08 term at North Texas.

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DSCI 3710 Exam1AMay2010Key - COURSE: DSCI 3710 Exam 1...

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