Answer: Our required probability is 0.304.
Step-by-step explanation:
Since we have given that
N = 21
Number of improperly drilled holes k = 4
Number of properly drilled holes = N-k= 21-4=17
Let X be the number of improperly drilled holes in a sample of 5.
We will use "Binomial distribution":
[tex]P(X=5)=\dfrac{^4C_0\times ^{17}C_5}{^{21}C_5}=0.304[/tex]
So, our required probability is 0.304.