Question

5. In a lot of 1000 bulbs, 20 are defective. What is the probability that a bulb chosen at random is not defective
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Answer 1

Answer:    $\frac{49}{50}$

Step-by-step explanation:

total no. of bulbs   ->1000

no. of non-defective bulbs  ->1000-20 = 980

Probability=$\frac{No. of possible outcomes}{no. of total outcomes}$=$\frac{980}{1000} =\frac{49}{50}$

Answer 2

Step-by-step explanation:

Total no. of bulb = 1000

No. of defective bulb = 20

∴ No. of non - defective bulb = 1000 - 20

                                                = 980

Now,

Probability of non-defective bulb = ( No. of non - defective bulb ) / ( Total no. of bulb )

                                                       = 980 / 1000

                                                       = 49 / 50

                                                       = 0.98        ( Ans)

HOPE THIS IS HELPFUL !!! : )