Question

A lot of 20 bulbs contain 4 defective ones. One bulb is drawn at random from the lot. What is the probability that this bulb is defective?

Answer 1

umber of all possible outcomes = 20.

Number of defective bulbs = 4.

Number of non-defective bulbs = 20 − 4 = 16.

Let E₁ be the event of getting a defective bulb.

∴ P(getting a defective bulb) = P(E₁) = `("Number of outcomes favourable to"  E_1)/"Number of all possible outcomes"`

`= 4/20`

`=1/5`                                                         

Thus, the probability that the bulb is defective is `1/5`.