Question 516518: 3. Approximately 20% of the independent grocery stores in Bonner County offer trading stamps. If a sample of 50 stores is selected, what is the probability that the proportion of stores offering trading stamps will be greater than 25%?
I need to know the correct formula for this problem
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Approximately 20% of the independent grocery stores in Bonner County offer trading stamps. If a sample of 50 stores is selected, what is the probability that the proportion of stores offering trading stamps will be greater than 25%?
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25% of 50 = 12.5
"greater than 25% will be from 13 to 50 stores.
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Binomial Problem with n = 50 and p = 0.20
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P(13 <= x <= 50) = 1 - binomcdf(50,0.2,12) = 0.1861
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Cheers,
Stan H.
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