A box has 20 pens of which 2 are defective. Calculate the probability that out of 5 pens drawn one by one with replacement, at most 2 are defective.

Explanation

To solve the problem of calculating the probability that out of 5 pens drawn one by one with replacement, at most 2 are defective, we can follow these steps:

### Step 1: Define the Problem
Let \( X \) be the random variable representing the number of defective pens drawn in 5 trials. We need to find the probability \( P(X \leq 2) \).

### Step 2: Identify the Parameters
- Total number of pens = 20
- Number of defective pens = 2
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