A certain law firm consists of 4 senior partners and 6 junior partners. How
many different groups of 3 partners can be formed in which at least one
member of the group is a senior partner? (Two groups are considered
different if at least one group member is different.)
(A) 48
(B) 100
(C) 120
(D) 288
(E) 600
At least one member of the group is a senior partner 有兩種算法
一：所有組合 減 組合都是junior 這我算出來是100 也是正確答案
二；三人團體中 一人是senior的組合 + 兩人是senior的組合 + 三人是senior的組合
(4x6x5)/3! + (4x3x6)/3! + (4x3x2)/3! = 36 不是100
第二個算法有哪邊錯了嗎？
因為圖書館要關了，一直找不到哪邊思考錯誤...
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