Thats a normal approximation to a Binomial with n=120 and p=.23

The mean is np and the VARIANCE is npq.

You want

where Y is Bin(120,.23)

Let X be our normal with the same mean and variance.

YOU should include the correction factor.

So

NOW center this X, by subtracting the mean (120)(.23)

and dividing by it's st dev

The answer will be

How's that 4 typing in TeX?

I had no idea of how you were doing it here.

NO one has helped me with my question.