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# Hypothesis Tests

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Chapter 9 Hypothesis Tests Learning Objectives 1 Learn how to formulate and test hypotheses about a population mean and or a population proportion 2 Understand the types of errors possible when conducting a hypothesis test 3 Be able to determine the probability of making various errors in hypothesis tests 4 Know how to compute and interpret p values 5 Be able to use critical values to draw hypothesis testing conclusions 6 Be able to determine the size of a simple random sample necessary to keep the probability of hypothesis testing errors within acceptable limits 7 Know the definition of the following terms null hypothesis alternative hypothesis Type I error Type II error one tailed test two tailed test p value level of significance critical value power curve 9 1 Chapter 9 Solutions 1 a H0 600 Manager s claim Ha 600 2 b We are not able to conclude that the manager s claim is wrong c The manager s claim can be rejected We can conclude that 600 a H0 14 Ha 14 3 4 b There is no statistical evidence that the new bonus plan increases sales volume c The research hypothesis that 14 is supported We can conclude that the new bonus plan increases the mean sales volume a H0 32 Specified filling weight Ha 32 Overfilling or underfilling exists b There is no evidence that the production line is not operating properly Allow the production process to continue c Conclude 32 and that overfilling or underfilling exists Shut down and adjust the production line a H0 220 Ha 220 5 Research hypothesis Research hypothesis to see if mean cost is less than 220 b We are unable to conclude that the new method reduces costs c Conclude 220 Consider implementing the new method based on the conclusion that it lowers the mean cost per hour a The Type I error is rejecting H0 when it is true In this case this error occurs if the researcher concludes that the mean newspaper reading time for individuals in management positions is greater than the national average of 8 6 minutes when in fact it is not b

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