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April 1st, 2007, 05:42 AM  #1 
Senior Member Joined: Dec 2006 From: New Jersey Posts: 378 Thanks: 1  Null Hypothesis and Test of Significance
Weekly sales of regular ground coffee at a supermarket have in the recent past varied according to a normal distribution with mean mu=354 units per week and std. dev. sigma =33 units. The store reduces the prce by 5%. Sales in the next three weeks are 405,378 and 411 units. Is this good evidence that average sales are now higher? Ho: mu = 354 Ha: mu > 354 a.)Find the value of the test statistic xbar b.)Sketch the normal curve for the sampling distribution of xbar when null hypothesis(Ho) is true. Shade the area that represents the Pvalue for the observed outcome. c.)Calculate the Pvalue d.)Is the result statistically significant at the alpha = .05 level? Is it significant at the alpha = .01? Do u think there is convincing evidence that mean sales are higher? 

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hypothesis, null, significance, test 
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