Probability Randomly Selected Question

Question

Usually, errors are found in 10% of lines of code written by software engineers at Error Free Code, Inc. What is the probability that in a randomly selected sample of 5 lines of code none of them have errors?

Answer 1

X is binomial with p=0.1,  N=5, k=0, and q = 1 - p = 0.9

 

(N choose k) * p^k * (q)^(n-k)

 

(5 choose 0) * (0.1)^0 * (0.9)^(5-0)

 

BUT (5 choose 0) , and any non-zero number to the power zero is 1

 

So the answer becomes:

  0.9^5 = .59049 = 59.049%