Homework SourseYou are testing lifespan of widgets and gadgets Select 107
You are testing lifespan of widgets and gadgets . Select 107 widgets and 116 for testing. 42 widgets failed and 47 gadgets failed. Conduct a test against hypoth that true rate of failure is the same against hypoth that they are different. What is test statistic?
-0.242
-0.192
0.589
-0.177
-0.951
-0.665
You are testing lifespan of widgets and gadgets . Select 107 widgets and 116 for testing. 42 widgets failed and 47 gadgets failed. Conduct a test against hypoth that true rate of failure is the same against hypoth that they are different. What is test statistic?
-0.242
-0.192
0.589
-0.177
-0.951
-0.665
-0.242
-0.192
0.589
-0.177
-0.951
-0.665
Solution
Formulating the hypotheses
Ho: p1^ - p2^ = 0
Ha: p1^ - p2^ =/= 0
Here, we see that pdo = 0 , the hypothesized population proportion difference.
Getting p1^ and p2^,
p1^ = x1/n1 = 0.392523364
p2 = x2/n2 = 0.405172414
Also, the standard error of the difference is
sd = sqrt[ p1 (1 - p1) / n1 + p2 (1 - p2) / n2] = 0.065621232
Thus,
z = [p1 - p2 - pdo]/sd = -0.192758487 = -0.192 [OPTION B]
