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 taken out is a good one.
Given:
- Number of defective pens = 12
- Number of good pens = 132
- Total pens = 12 + 132 = 144
Favourable outcome:
We want a good pen, and there are 132 good pens.
So, the probability is:
Probability = Number of good pens / Total number of Pens
132/144 = 11/12