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Homework 4

Due date: Thursday, Nov. 16, 2017.

Note: all hypothesis testing problems should include the null and alternative hypotheses and report the p-value of the data.

  1. A company is said to be out of compliance if more than 7% of all invoices contain errors, and it is said to be seriously out of compliance if more than 10% of all invoices contain errors. Suppose an auditor randomly selects a sample of 1000 invoices and finds that 120 contained errors.

  2. A large corporation has a plant that has started a pilot program to give stock options for its assembly line workers as part of their benefits package. The corporation would like to determine if the mean quality score for this plant exceeds the current average quality measure of 82. A random sample of 25 production units is selected from this plant and the quality scores for these units are obtained. The sample mean score for these units is 86.2 with a s.d. of 10.4.

  3. A random sample of 48 students took an SAT preparation course prior to taking the SAT. The sample mean of their quantitative SAT scores was 560 with a s.d. of 80, and the sample mean of their verbal SAT scores was 520 with a s.d. of 110.

  4. A fabrication plant has just completed a contract to supply memory chips to a computer manufacturer that requires the defective rate of these chips to be no more than 6%. The plant has just installed new equipment to produce these chips. An initial production run of 500 chips will be obtained and one of three actions will be taken depending on the results of this run. If it is shown that more than 6% of the chips are defective, then the equipment will be recalibrated to reduce the defective rate; if it is shown that fewer than 6% of chips are defective, then cheaper raw material will be used to reduce costs; otherwise, the equipment will be unchanged and production will begin. Suppose that among the initial production of 500 chips it was found that 40 chips were defective.


next up previous
Next: Summary of Methods Up: Homework and Project Assignments Previous: Homework 3
ammann
2017-11-16