Suppose I have 10,000 data points with the following statistics:
Sample mean: 7
Sample variance: 4.2 (and hence standard deviation 2.05)
Population mean is also 7.
Now if I increase the sample size to 12,000 (1.2 times larger), how do I estimate the new variance (if that possible)?
I think the variance will also be 1.2 times smaller, but I'm not sure.