✨ Jawaban Terbaik ✨
7. 取1的期望值的算式,機率是⅓不是⅑
24.
P(最大=1) = 0
P(最大=2) = C⁴₃/C⁸₃ = 4/56 = 1/14
P(最大=3) = [C⁶₃-C⁴₃]/C⁸₃ = (20-4)/56 = 16/56 = 2/7
P(最大=4) = [C⁸₃-C⁶₃]/C⁸₃ = (56-20)/56 = 36/56 = 9/14
E = 1·0 + 2·1/14 + 3·2/7 + 4·9/14
= 1/7 + 6/7 + 18/7
= 25/7
了解了!非常感謝~