Given the following set of values:

10,11,14,95,73,30,29,9,97,94,70

How do I calculate a 99% confidence interval for the sample mean? I am assuming that the variance is 10

Well, the idea I have is to assume that the distribution is normal, but after that i'm not completely sure what to do next. In particular, I am unable to find the z-score that corresponds to the z-score in the formula for the CI, i'm not sure what to input in R to find the CI. The formula for the confidence interval is:

$x-{z}_{\frac{a}{2}}\frac{{\sigma}^{2}}{sqrt(n)}$ and $x+{z}_{\frac{a}{2}}\frac{{\sigma}^{2}}{sqrt(n)}$ where x denotes the mean. Here the significance level (a) is 0.01.