Question 187925
A coin was flipped 80 times and came up tails 54 times. At the 0.05 level of significance, is the coin biased toward tails? Show your decision rule and calculations.
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Ho: p = 1/2
Ha: p > 1/2
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sample proportion: 54/80 = 0.675
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test statistic: z(0.675) = (0.675-0.5)/sqrt((1/2)(1/2)/80) =  3.1305
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Critical value for right-tail test with alpha=5%: z=-1.96 or z=1.96
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p-value = 2(P(z>1.96)) = 2(0.000873) = 0.0017
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Decision Rule: If p-value is less than 5%, reject Ho.
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Conclusion: Since p-value is less than 5%, reject Ho ; the cois is
biased toward heads.
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Cheers,
Stan H.
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