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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?
Solution
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`.
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