题目
Using the following Information to answer the question below.「huixue_img/importSubject/1564169386204467200.png」The variance of X is closest to:
选项
A.0.58
B.0.59
C.0.60
D.0.61
答案
D
解析
p(X = 1) = 0.05 + 0.05 + 0.10 = 0.20p(X = 2) = 0.05 + 0.10 + 0.15 = 0.30p(X = 3) = 0.15 + 0.15 + 0.20 = 0.50E(X) = 0.2×1 + 0.3×2 + 0.5×3 = 2.3V(X) = 0.2×(1-2.3)^2 + 0.3×(2-2.3)^2 + 0.5×(3-2.3)^2 = 0.61