A company wants to recruit three people from the interviewers. Assuming that everyone who attends the interview has the same probability of being hired, the probability of two people being hired at th

A company wants to recruit three people from the interviewers. Assuming that everyone who attends the interview has the same probability of being hired, the probability of two people being hired at the same time is 70. Suppose that X people (x≥3) participated in the recruitment interview of this unit.

Then the probability of two people being recruited at the same time is Cx-2 superscript 1/Cx superscript 3= 1/70.

That is 6 (x-2)/[x (x-1) (x-2)] =1/70.

That is x(x- 1)=420,

∴(x-2 1)(x+20)=0，

The solution is x = 2 1.