Suppose you have a company with four markets in four regions (eg China, United States, United Kingdom, Japan).

Suppose you have a company with four markets in four regions (eg China, United States, United Kingdom, Japan). The distribution of their sales is a normal distribution with a mean of 100 and a standard deviation of 0.5. What is the distribution of the total market, and what are the average and standard deviations? If these four markets are not independent, what is the distribution?