Estimating (insert u shaped symbol) with large Samples

[wordsthroughmusic]

Ok. Here's my issue. I do not know how to do this. I don't get it.
Here's an example that I got and I don't know how to do it. Can someone help me?

In an article exploring blood serum levles of vitamins and lung cancer risks (The New England Journal of Medicine), the mean serum level of vitamin E in the control group was 11.9 mg/liter with standard deviation 4.30 mg/liter. There were 196 patients in the control group (These patients were free of all cancer, except possibly skin cancer, in the subsequent 8 years). Using this information, the zc value for a 95% confidence interval would be ____________?

 

[tkhunny]

What's a "zc value"?

Something like this, maybe? \(\displaystyle 11.9 + z_{0.025}*\frac{4.3}{\sqrt{196}}\)

Does that thing look familiar at all?