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sparkle · 2022年02月09日

题目应该改成65% of all companies have scanners.... what is the probability that all five companies would have scanners

NO.PZ2015120604000089

问题如下:

According to the research, 65% of all companies have a scanner.  Assuming we selected 8 companis, what is the probability that  five companies would have a scanner ?

选项:

A.

0.138.

B.

0.311.

C.

0.279.

解释:

C is correct.

[8!/5!(8- 5)!](0.65) 5 (0.35) 8 - 5 = 56*(0.1160)*(0.04288) =0.279.

题目应该改成65% of all companies have scanners.... what is the probability that all five companies would have scanners ,否则读起来有歧义

1 个答案

星星_品职助教 · 2022年02月10日

同学你好,

have scanners 和 have a scanner是同义;

what is the probability that five companies would have a scanner是二项分布的问法,指的是8家中的5家,此处没有必要加all