Q8 of 54 Page 320

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 is defective. One pen is taken out at random from this lot. Determine the probability that the pen taken out is a good one.

Given,

⇒ Total defective pens = 12


⇒ Total good pens = 132


∴ number of favourable cases = 132


⇒ Total number of pens = 12 + 132


⇒ Total number of pens = 144


⇒ Number of total outcomes will 144.


⇒ Probability that the pen taken out is a good one =


⇒ P(pen taken out is good one) =


⇒ P(pen taken out is good one) =


∴ Probability of pen taken out is good one is


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