On a particular production line the likelihood that a light

On a particular production line, the likelihood that a light bulb is defective is 5%. Ten night bulbs are randomly selected. What is the probability that two of the light bulbs will be defective?

Solution

Let X be the random variable denoting the no. of defective bulbs.
Therefore, the probability that two of the light bulbs will be defective is
C ( 10,2 ) * [ ( .05 ) ^ 2 ) * ( (.95) ^ 8) ) ]
= 0.0746348
As, X follows Binomial ( 10, .05),