数学高手进啊!大学的统计学的作业,已然不会做。求助攻啊,需要过程,非常感谢!

9.5Anormallydistributedpopulationhasameanof40andastandarddeviationof12.Whatdoesthecen... 9.5 A normally distributed population has a mean of 40and a standard deviation of 12. What does the central limit theorem say aboutthe sampling distribution of the mean if samples of size 100 are drawn fromthis population?

9.20. The marks on a statistics midterm test are normallydistributed with a mean of 78 and a standard deviation of 6.
1. What proportion of theclass has a midterm mark of less than 75?
Answer0.3085
2. What is theprobability that a class of 50 has an average midterm mark that is less than75?
Answer0

9.22.
The manufacturer of cans of salmon that are supposedto have a net weight of 6 ounces tells you that the net weight is actually anormal random variable with a mean of 6.05 ounces and a standard deviation of.18 ounces. Suppose that you draw a random sample of 36 cans.
1. Find the probabilitythat the mean weight of the sample is less than 5.97 ounces.

2. Suppose your randomsample of 36 cans of salmon produced a mean weight that is less than 5.97ounces. Comment on the statement made by the manufacturer.

9.39.
The Laurier Company’s brand has a market share of30%. Suppose that 1,000 consumers of the product are asked in a survey whichbrand they prefer. What is the probability that more than 32% of therespondents say they prefer the Laurier brand?

9.51.
A factory’s worker productivity is normallydistributed. One worker produces an average of 75 units per day with a standarddeviation of 20. Another worker produces at an average rate of 65 per day witha standard deviation of 21. What is the probability that in 1 week (5 workingdays), worker 1 will outproduce worker 2?
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