Question 544786
Suppose you are testing the hypotheses: 
H0: p1 = p2 
Ha: p1 < p2 
And X1 = 20 successes, n1 = 45, x2 = 15 successes, n2 = 40
p1hat = (20/45) = 4/9 ; p2hat = (15/40) = 3/8
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a. Calculate the z-score
test statistic = z(4/9 - 3/8) 
= z(5/(72)) = (5/72)/sqrt[(4/9*5/9)/45 + (3/8*5/8)/40]
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b. State the formula used to estimate the p-value: 
p-value = P(z < test statistic)
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Cheers,
Stan H.