SOLUTION: Please help me solve statistics question. The weight of 10000 items are normally distributed with a mean of 115kg and a standard deviation of 3kg. Find the probability that the

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Question 1088069: Please help me solve statistics question.
The weight of 10000 items are normally distributed with a mean of 115kg and a standard deviation of 3kg. Find the probability that the average weight of 40 randomly selected items will be above 115 kg.

Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
sample standard deviation = population standard deviation / square root sample size
:
sample standard deviation = 3 / square root(40) = 0.47
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sample mean is equal to the population mean
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Probability(P) ( X > 115 ) = 1 - P( X < 115)
:
z-score = 115 - 115 / 0.47 = 0
:
P ( X < 115 ) = 0.50
:
P ( X > 115 ) = 1 - 0.50 = 0.50
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