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.

Explanation

To solve the problem of determining the probability that a pen taken out at random is a good one, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the number of defective and good pens:**
- Number of defective pens = 12
- Number of good pens = 132

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