Question

A carton of 24 bulbs contain 6 defective bulbs. One bulbs is drawn at random. What is the probability that the bulb is not defective? If the bulb selected is defective and it is not replaced and a second bulb is selected at random from the rest, what is the probability that the second bulb is defective?

Answer 1

∴ Total number of bulbs, n(S) = 24

Let E₁ = Event of selecting not defective bulb

= Event of selecting good bulbs

n(E₁) = 18

∴ `P(E_1) = (n(E_1))/(n(S)) = 18/24 = 3/4`

Suppose, the selected bulb is defective and not replaced, then total number of bulbs remains in a carton, n(S) = 23.

In them, 18 are good bulbs and 5 are defective bulbs.

∴ P(selecting second defective bulb) = `5/23`