SOLUTION: 30 % of firm’s orders come from new customers. A simple random sample of 100 orders will be used to estimate the proportion of new customers. Find probability that sample proportio

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Question 304738: 30 % of firm’s orders come from new customers. A simple random sample of 100 orders will be used to estimate the proportion of new customers. Find probability that sample proportion will be between 0.22 and 0.40
Answer by stanbon(57219) About Me  (Show Source):
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30 % of firm’s orders come from new customers. A simple random sample of 100 orders will be used to estimate the proportion of new customers. Find probability that sample proportion will be between 0.22 and 0.40
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p = 0.3
sigma = sqrt(pq) = sqrt(0.3*0.7)
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z(0.22) = (0.22-0.30)/[sqrt(0.3*0.7/100)] = -1.7457
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z(0.40) = (0.40-0.30)/[sqrt(0.3*0.7/100)] = 2.1822
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P(0.22 < p < 0.40) = P(-1.7457 < z < 2.1822) = 0.9450
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Cheers,
Stan H.
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