Calculate the variance and standard deviation for samples with the following statistics. a. n = 10, Xx2 = 81, Ex = 20 b. n = 38, _x2 = 378, Ex = 100 c. n = 22, Xx2 = 14, Ex = 13 a. The variance is 4.556 . The standard deviation is 2.134. (Round to the nearest thousandth as needed.) b. The variance is 3.104. The standard deviation is 1.762 . (Round to the nearest thousandth as needed.) c. The variance is The standard deviation is (Round to the nearest thousandth as needed.)