Question

A company has 200 machines. Each machine has 12% probability of not working.

Answer 1

1) This probability is given by

... C(40,5)·0.12⁵·0.88³⁵ ≈ 0.18665 . . . . . where C(n, k) = n!/(k!(n-k)!)

2) This probability is given by

... 0.88⁴⁰ ≈ 0.00602

3) This is the complement of the probability that all have failed.

... 1 - 0.12⁴⁰ ≈ 1.0000