from the lot of 30 bulbs which include 6 defectives , a sample of 4 bulbs is drawn with replacement . find the prob. distribution of the no. of defective bulbs.

Asked by prabhakar p | 14th Mar, 2013, 06:48: AM

Expert Answer:

Whenever, the question is talking about the replacements, you should not use combinations, untill and unless you are treating each event(or draw) as an independent. 
 
In this case, probability of drawing a defective bulb = (30-6)/30 = 24/30 = 4/5
Probability of drawing a defective bulb = 1/5. 
 
Now, let X be the number of defective bulbs drawn

Answered by  | 14th Mar, 2013, 07:25: AM

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