If I have the following information
(A) 5%, 10%, 15%, 4% = 5+10+15+4 = 34%
Sum 34%/4 Years = Average Return 8.5%

How do I find the Variance,
Standard deviation
Coefficient variation

You have the sum and the average. Subtract the average from each of the values and square it. Add up the squared values and divide by "n-1", one less than the number of entries. In this case, 3. That is the standard variation.