alleryX ~ Binomial(50, 0.4). Find E[X] and Var[X]:
A20 and 25
B0.4 and 0.6
C50 and 25
D20 and 12 (= 50 × 0.4 and 50 × 0.4 × 0.6)
Answer & Solution
Correct answer: D. 20 and 12 (= 50 × 0.4 and 50 × 0.4 × 0.6)
E[X] = np = 50 × 0.4 = 20. Var[X] = np(1-p) = 50 × 0.4 × 0.6 = 12.
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