Question

I'm doing a right tailed test for the population mean. I am using 5% signifigance, I know the population standard deviation, and my test statistic is 1.88. What is the p-value? Would you reject the null hypothesis?

Answer 1

Here we know the population standard deviation, so the given test for testing population mean is right tailed Z-test.

So the p-value = P( Z > Z_test ) = P( Z > 1.88) = 1 - P( Z < 1.88 ) ....( 1 )

From Z-table , P(Z < 1.88) = 0.9699

Plug this value in equation 1), we get .

p-value = 1 - 0.9699 = 0.0301

Decision rule:

1) If p-value < level of significance (alpha) then we reject null hypothesis

2) If p-value > level of significance (alpha) then we fail to reject null hypothesis.

Here p value = 0.0301 < 0.05 so we used first rule.

That is we reject null hypothesis.