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The solution would be like this for this specific problem:
H0: p = p0, orÂ
H0: p ≥ p0, orÂ
H0: p ≤ p0Â
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find the test statistic z = (pHat - p0) / sqrt(p0 * (1-p0) / n)Â
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where pHat = X / nÂ
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The p-value of the test is
the area under the normal curve that is in agreement with the alternate
hypothesis.Â
H1: p ≠p0; p-value is the area in the tails greater than |z|Â
H1: p < p0; p-value is the area to the left of zÂ
H1: p > p0; p-value is the area to the right of zÂ
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Hypothesis equation:
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H0: p ≥ 0.67 vs. H1: p < 0.67Â
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The test statistic is:Â
z = ( 0.5526316 - 0.67 ) / ( √ ( 0.67 * (1 - 0.67 ) / 38 )Â
z = -1.538681Â
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The p-value = P( Z < z
)Â
= P( Z < -1.538681 )Â
= 0.0619