Question
(i) 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?(ii) Suppose the bulb drawn in (i) is not defective and is not replaced. Now one bulb is drawn at random from the rest. What is the probability that this bulb is not defective ?
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Solution: (i) Here, total number of bulbs
Number of defective bulbs
So, probability of drawing a defective bulb
(ii)If drawn bulb is not defective and not replaced, then
Remaining number of total bulbs
Remaining number of defective bulbs
So,remaining number of non-defective bulbs
Probability of drawing a non-defective bulbs
Number of defective bulbs
So, probability of drawing a defective bulb
(ii)If drawn bulb is not defective and not replaced, then
Remaining number of total bulbs
Remaining number of defective bulbs
So,remaining number of non-defective bulbs
Probability of drawing a non-defective bulbs
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Question Text | (i) 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?(ii) Suppose the bulb drawn in (i) is not defective and is not replaced. Now one bulb is drawn at random from the rest. What is the probability that this bulb is not defective ? |
Answer Type | Text solution:1 |
Upvotes | 150 |