An um contains 5 red and 5 black balls. A ball is drawn at random, its colour is noted and is returned to the urn. Moreover, 2 additional balls of the colour drawn are put in the um and then a ball is drawn at random. What is the probability that the second ball is red?

Explanation

To solve the problem step by step, we will analyze the situation and calculate the required probabilities.

### Step 1: Understand the Initial Setup
The urn contains 5 red balls and 5 black balls. Therefore, the total number of balls in the urn is:
- Red balls = 5
- Black balls = 5
- Total balls = 5 + 5 = 10

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