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12 defective pens are accidentally mixed with 132 good ones. It is not possible to just look at a pen and tell whether or not it is defective. One pen is taken out at random from this lot. The probability that the pen taken out is a good one is

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0.156

0.396

0.518

0.917

answer is D.

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Detailed Solution

It is given that 12 defective pens are accidentally mixed with 132 good ones.
The probability of an event E is given as;

P (E) = N u m b e r o f o u t c o m e s f a v o u r a b l e t o E N u m b e r o f a l l p o s s i b l e o u t c o m e s o f t h e e x p e r i m e n t

Number of defective pens = 12
Number of good pens = 132
Therefore, total number of pens

= 12 + 132 = 144

∴ P g e t t i n g a g o o d p e n = N u m b e r o f g o o d p e n s T o t a l n u m b e r o f p e n s = 132144 = 1112 ≈ 0.917

Therefore, the probability that the pen taken out is a good one is 0.917.
Hence option (4) is correct.

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