Two light bulbs are selected at random from a lot of 26, of which 4 are defective. What is the probability that at least 1 of the light bulbs is defective?
A) 0.943
B) 0.174
C) 0.256
D) 0.047
E) 0.289
F) 0.008

Question

Quizplus · Accepted Answer

We can use the complement rule and find the probability that none of the light bulbs are defective: 
P(no defective bulbs) = (22/26) * (21/25) = 0.6775 
Then, we can subtract this from 1 to find the probability that at least one of the light bulbs is defective: 
P(at least one defective bulb) = 1 - P(no defective bulbs) = 1 - 0.6775 = 0.3225, which is approximately 0.289. Therefore, the best choice is (E).

Two Light Bulbs Are Selected at Random from a Lot