Test statistics help needed It has been claimed that at U.C.L.A. at least 40% of the students live on campus. From a sample of 250 students, 90 live on campus. Does the evidence support this claim at a = 0.01 . What i did is Ho: P is greater or equal to 0.4 Ha: P is less than 0.4 The critical value comes out to be -2.33 from the table Now how to calculate the test statistics?

This is a statistics question (there's a forum for that) but I will answer anyway:

The sample proportion is $$\frac{90}{250}=0.36$$ so the sample standard error is $$\sqrt{\frac{0.36\cdot 0.64}{250}}\approx0.03$$ The $z$-score is therefore $$z=\frac{0.36-0.40}{0.03}=-1.33$$

You critical value looks wrong, I think at $99$% confidence you should have something like $2.56$?

Regardless, this will not be enough to reject the null hypothesis.