Q6:
A certain company assigns employees to offices in such a way that some of the offices can be empty and more than one employee can be assigned to an office. In how many ways can the company assign 3 employees to 2 different offices?
A. 5
B. 6
C. 7
D. 8
E. 9
为什么是D,我怎么排出了是9呢?大家帮我解释一下,谢谢
Q14:
If a code word is defined to be a sequence of different letters chosen from the 10 letters A, B, C, D, E, F, G, H, I, and J, what is the ratio of the number of 5-letter code words to the number of 4-letter code words?
A. 5 to 4
B. 3 to 2
C. 2 to 1
D. 5 to 1
E. 6 to 1
Answer:
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Q6:C(3,0)+C(3,1)+C(3,2)+C(3,3)=8
Q14:选D吧,P(10,5)/P(10,4)=5/1
Q14:选D吧,P(10,5)/P(10,4)=5/1
应该是C(10,5)/C(10,4)吧,哎,我怎么算出来不对啊,是6:5啊
(10*9*8*7*6)/(5*4*3*2) 再去除(10*9*8*7)/(4*3*2*1) , 得出来6:5,我哪里出问题了,好象都答出来是5:1吗,如果是P(10,5)/P(10,4)的话应该是6:1啊
Q6:C(3,0)+C(3,1)+C(3,2)+C(3,3)=8 同意是对的 但是和答案不一样不放心
Q14:选D吧,P(10,5)/P(10,4)=5/1 同意公式 6:1 但好象算错了
C(10,5)5个被选出的字母应该可以排序的欢迎光临 ChaseDream (https://forum.chasedream.com/) | Powered by Discuz! X3.3 |