Question

In a large shipment of clocks, it has been discovered that 15 % of the clocks are defective. Suppose that you choose 9 clocks at random. What is the probability exactly 2 of the clocks are defective.

Answer 1

Solution

Given that ,

p = 0.15

1 - p = 0.85

n = 9

Using binomial probability formula ,

P(X = x) = (_n C _x) * p^x * (1 - p)^{n - x}

P(X = 2) = (₉ C ₂) * 0.15² * (0.85)⁷

= 0.2597

Probability = 0.2597