What I mean by "violate" is that we ask you to give the entire problem, and what you are able to do with it, and you didn't. If you're saying you gave us everything you were given, and you have been taught nothing about the topic, then THEY (whoever they are) are doing something wrong.
Can you at least tell us the context of your question? Is this an assignment you were given? If not, do you have some particular goal? Anything else you can tell us, can help us know how to answer effectively.
One way or another, you have to tell us what the inputs are, in order to say anything about doing something in Excel.
But let's see what I can say, with no context.
What you gave us was the inequality [MATH]\overline{x} - z_{\alpha/2}\cdot\frac{\sigma}{\sqrt{n}}\lt\mu\lt\overline{x} + z_{\alpha/2}\cdot\frac{\sigma}{\sqrt{n}}[/MATH]. This is not exactly "a formula"; it says that [MATH]\mu[/MATH] will be between two numbers. So my first comment is that all you can do is to calculate those two numbers, which define an interval within which [MATH]\mu[/MATH] must lie. You will have to know the meaning of those numbers, in your context.
How to calculate those numbers depends on what you are given. It will be one thing if you are given values for [MATH]\overline{x}[/MATH], [MATH]z_{\alpha/2}[/MATH], [MATH]\sigma[/MATH], and [MATH]n[/MATH]. It will be another if you are given data (from a survey, say) and have to calculate those numbers. Or, maybe you have something in between, such as [MATH]\alpha[/MATH] from which you have to calculate [MATH]z_{\alpha/2}[/MATH].
That's why we need more information.