Sets A and B each contain 10 observations. For both sets, the mean of the squares of observations is 50. The arithmetic mean of A is 5, while that of B is 6. Which statement is correct regarding their variances?
a) Variance of A equals variance of B
b) Variance of B is greater than variance of A
c) Variance of A is greater than variance of B
d) The given data are insufficient to compare the variances