If coefficient of correlation `r=-1`, then r is called ……………..

Answer

To solve the question, we need to understand the meaning of the correlation coefficient \( r \).

### Step-by-Step Solution:

1. **Understanding Correlation Coefficient**: The correlation coefficient \( r \) is a statistical measure that describes the strength and direction of a relationship between two variables. The value of \( r \) can range from -1 to 1.

2. **Identifying the Value of \( r \)**: In this case, we are given that \( r = -1 \).

3. **Interpreting \( r = -1 \)**: When \( r \) is equal to -1, it indicates a perfect negative correlation between the two variables. This means that as one variable increases, the other variable decreases in a perfectly linear manner.

4. **Conclusion**: Therefore, if the correlation coefficient \( r \) is -1, we call it "perfectly negatively correlated".

### Final Answer:
If the coefficient of correlation \( r = -1 \), then \( r \) is called **perfectly negatively correlated**.

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