proboility QS

Question

The probability that Big Co. will hire new graduates from State U. who have interviews in any given year is 30%. Of the graduates this year, 9 were chosen at random for interviews. What is the probability that exactly 3 of them will be hired?

Answer 1

30% hired

pick 9 at random what is the chance exactly 3 will be hired

0 hired (.7)^9

1 hired 9)(.3(9.7)^8

2 hired 36(.3^2)(.7^7)

3 hired 9C3(.3^3)(.7^6)=

= 84(.0027)(.49)(.49)(.49)

=about 26.68%