Insert one rational number between `3 "and" 4`.

Answer

To insert one rational number between 3 and 4, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the two numbers**: We are given the numbers 3 and 4.

2. **Find the average of the two numbers**:
- The formula for the average of two numbers \( x \) and \( y \) is given by:
\[ \text{Average} = \frac{x + y}{2} \]
- Here, \( x = 3 \) and \( y = 4 \).

3. **Calculate the average**:
- Substitute the values into the formula:
\[ \text{Average} = \frac{3 + 4}{2} = \frac{7}{2} \]

4. **Convert the result to decimal** (if needed):
- \(\frac{7}{2} = 3.5\)

5. **Check if it is a rational number**:
- A rational number is defined as a number that can be expressed in the form \(\frac{p}{q}\), where \( p \) and \( q \) are integers and \( q \neq 0\).
- Here, \( \frac{7}{2} \) meets this criterion since 7 and 2 are integers, and 2 is not equal to 0.

### Conclusion:
Thus, one rational number between 3 and 4 is \( \frac{7}{2} \) or 3.5.

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