Solution:-
11.33)
State the hypotheses. The first step is to state the null hypothesis and an alternative hypothesis.
Null hypothesis: P1 - P2 < 0
Alternative hypothesis: P1 - P2 > 0
Note that these hypotheses constitute a one-tailed test.
Formulate an analysis plan. For this analysis, the significance level is 0.01. The test method is a two-proportion z-test.
Analyze sample data. Using sample data, we calculate the pooled sample proportion (p) and the standard error (SE). Using those measures, we compute the z-score test statistic (z).
p = (p1 * n1 + p2 * n2) / (n1 + n2)
p = 0.30
SE = sqrt{ p * ( 1 - p ) * [ (1/n1) + (1/n2)
] }
SE = 0.05684
z = (p1 - p2) / SE
z = 2.815
where p1 is the sample proportion in sample 1, where p2 is the sample proportion in sample 2, n1 is the size of sample 1, and n2 is the size of sample 2.
Since we have a one-tailed test, the P-value is the probability that the z-score is greater than 2.815.
Thus, the P-value = 0.0024.
Interpret results. Since the P-value (0.024) is greater than the significance level (0.01), we cannot reject the null hypothesis.
From the above test we do not have sufficient evidence in the favor of the claim that the proportion of managers expecting the higher rates diminished in July.
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