SOLUTION: Parts being manufactured at a plant are supposed to weigh 70 grams. Suppose the distribution of weights has a Normal distribution with mean 76 grams and a standard deviation of 2
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Question 1187835: Parts being manufactured at a plant are supposed to weigh 70 grams. Suppose the distribution of weights has a Normal distribution with mean 76 grams and a standard deviation of 20 grams. Quality control inspectors randomly select 256 parts, weigh each, and then compute the sample average weight for the 256 parts. Find The probability that the mean weight of these 256 parts is more than 80 grams or less than 72 grams is (Round to two decimals throughout and write as a % to 2 decimal places) Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website! z test used
z>(80-76)/20/sqrt(256), difference in means divided by sigma/sqrt(n)
> 4*16/20
>3.2
-
z< 72 is <-3.2
the probability of each of these is 0.00069
The combined probability is 0.00138 or .14%
