he Environmental Protection Agency wanted to compare the proportion of plants in
ID: 2948061 • Letter: H
Question
he Environmental Protection Agency wanted to compare the proportion of plants in violation of air quality standards for two different industries: steel and utility. Two independent samples of plants were selected and monitored. The following data was recorded:
Steel: n1 = 150 Number of violations =x1 = 12
Utility: n2 = 160 Number of violations = x2 = 12
Test using ? = 0.01.
The null and alternate hypothesis used:
H0: p1-p2=0 vs. Ha: p1-p2 not equal 0
The test statistic is:
0.1645
What is the correct conclusion regarding this test?
There is not enough information given
Reject the null hypothesis
Accept the null hypothesis
Fail to reject the null hypothesis
A.There is not enough information given
B.Reject the null hypothesis
C.Accept the null hypothesis
D.Fail to reject the null hypothesis
Explanation / Answer
As the alternative hypothesis here is testing from both sides, therefore this is a two tailed test, therefore the p-value here is computed from the standard normal tables as:
p = 2P( Z > 0.1645 ) = 2*0.4347 = 0.8694
Therefore the p-value here is 0.8694 > 0.01 which is the level of significance, therefore the test is not significant and we cannot reject the null hypothesis here.
Therefore D is the correct answer here.
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