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Unformatted text preview: Answers to a One Sample t Test The following will assist you in understanding more the hypothesis process, and prepare you for the Applications 1 activity in Week Two. &quot;The mean life of a battery used in a digital clock is 305 days. The lives of the batteries follow the normal distribution. The battery was recently modified to last longer. A sample of 20 of the modified batteries had a mean life of 311 days with a sample standard deviation of 12 days. Did the modification increase the mean life of the battery? The level of significance for this problem is 0.05. Setup the null hypothesis and alternative hypothesis. Ho: 305 H 1 : &gt; 305 Note that in a hypothesis set up we are looking for one of three possibilities that the &quot;situation&quot; is asking: is there a difference in the mean, is there an increase from the mean, or is there a decrease from the mean? I have put the key words in bold. In the &quot;last sentence&quot; above, note the key word is increase. Important: when there is a direction (increase/more than or a decrease/less than) that direction is always in the alternative. If there is no a direction (increase/more than or a decrease/less than) that direction is always in the alternative....
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This note was uploaded on 10/10/2010 for the course STATS Stats301 taught by Professor Regis during the Spring '10 term at DeVry Irvine.
 Spring '10
 Regis
 Statistics

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