Question

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

1) If you were to pick 40 machines randomly, the probability that 5 would not be working is_____

2) The probability that all would be working is______

3) And the probability that at least one machine would be working is______

Answer 1

1)0.187

2)0.006

3)1

Explanation:

Plato users.

Answer 2

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