12 defective pens are accidentally mixed with 132 good ones. It is not

1.	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. Determine the probability that the pen is taken out is a good one.
Answer» Numbers of pens = Numbers of DEFECTIVE pens + Numbers of good pens ∴ Total NUMBER of pens = 132 + 12 = 144 pens P (E) = (Number of favourable OUTCOMES) / (Total number of outcomes) P (picking a good pen) = 132/144 = 11/12 = 0.916

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. Determine the probability that the pen is taken out is a good one.

Answer»

Numbers of pens = Numbers of DEFECTIVE pens + Numbers of good pens

∴ Total NUMBER of pens = 132 + 12 = 144 pens

P (E) = (Number of favourable OUTCOMES) / (Total number of outcomes)

P (picking a good pen) = 132/144 = 11/12 = 0.916