# The distribution of actual weights of 8 ounce

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1.The distribution of actual weights of 8-ounce chocolate bars produced by a certain machine isNormal with mean 8.1 ounces and standard deviation 0.1 ounces.Company managers do notwant the weight of a chocolate bar to fall below 7.85 ounces, for fear that consumers willcomplain.(a)Find the probability that the weight of a randomly selected candy bar is less than 7.85ounces.Four candy bars are selected at random and their mean weight,x, is computed.(b) Describe the center, shape, and spread of the sampling distribution ofx(c)Find the probability that the mean weight of the four candy bars is less than 7.85 ounces.(d)Would your answers to (a), (b), or (c) be affected if the weights of chocolate bars producedby this machine were distinctly non-Normal?Explain..
320The Practice of Statistics, 4/e- Chapter 7© 2011 BFW Publishers2.Suppose you roll a six-sided 50 times and calculate the mean roll,.(a) We can consider these 50 rolls as a SRS of rolls from the population of all possible rolls ofthis die.Using formulas from Chapter 6, we can determine that if the die is fair, the mean ofthis population is 3.5 and the standard deviation 1.71.How would you describe the shape ofthis population distribution?(b) Find the shape, center, and spread of the sampling distribution of.(c) Suppose that the mean of your 50 rolls is3.25.xAre you suspicious about the fairness ofthe die?Justify your answer.xx
Test 7AAP StatisticsName:Part 1:Multiple Choice.Circle the letter corresponding to the best answer.1.Following a dramatic drop of 500 points in the Dow Jones Industrial Average in September1998, a poll conducted for the Associated Press found that 92% of those polled said that a yearfrom now their family financial situation will be as good as it is today or better.Which of thefollowing terms describes the number 92%?
2.What is distribution of values taken by a statistic in all possible samples of the same size fromthe same population called?
3.If a statistic used to estimate a parameter is such that the mean of its sampling distribution isequalto the true value of the parameter being estimated, what is the statistic said to be?
© 2011 BFW PublishersThe Practice of Statistics, 4/e- Chapter 7321

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