题目
A firm will select two of four vice presidents to be added to the investment committee. How many different groups of two are possible?
选项
A.6
B.12
C.24
答案
A
解析
A is correct. The answer is found using the combination formula「huixue_img/importSubject/1564548695226191872.png」Here, n = 4 and r = 2, so the answer is 4!/[(4 – 2)!2!] = 24/[(2) × (2)] = 6. This result can be verified by assuming there are four vice presidents, VP1–VP4. The six possible additions to the investment committee are VP1 and VP2, VP1 and VP3, VP1 and VP4, VP2 and VP3, VP2 and VP4, and VP3 and VP4.. A正确。 使用组合公式:n = 4 r = 2，所以答案是4!/ ((4 - 2),2 != 24/[(2)×(2)]= 6。这个结果可以通过假设有四个副总裁来验证，VP1到VP4。 选两个加入到委员会中，那么投资委员会可能增加的成员将有以下6种组合，分别是:VP1和VP2、VP1和VP3、VP1和VP4、VP2和VP3、VP2和VP4、VP3和VP4。