We can estimate the value of one variable with the help of other known variable only if they are

Options

A. Correlated
B. Positively correlated
C. Negatively correlated
D. Uncorrelated

Answer

To solve the question "We can estimate the value of one variable with the help of another known variable only if they are...", we need to analyze the concept of correlation between two variables.

### Step-by-Step Solution:

1. **Understanding the Question**: The question is asking under what condition we can estimate the value of one variable using another known variable.

**Hint**: Think about how two variables can influence each other.

2. **Defining Correlation**: Correlation refers to a statistical measure that describes the extent to which two variables change together. If two variables are correlated, it means that when one variable changes, the other variable tends to change in a specific direction (either positively or negatively).

**Hint**: Recall the definition of correlation and its significance in statistics.

3. **Types of Correlation**: There are different types of correlation:
- Positive Correlation: Both variables move in the same direction.
- Negative Correlation: One variable increases while the other decreases.
- No Correlation: There is no predictable relationship between the variables.

**Hint**: Consider how the direction of change in one variable affects the other.

4. **Application of Correlation**: In practical scenarios, such as finance, we can estimate the value of a stock based on its correlation with a benchmark index. If the stock price and the index are correlated, knowing the index's value can help us estimate the stock's value.

**Hint**: Think of real-world examples where correlation is used to predict outcomes.

5. **Conclusion**: Therefore, the correct answer to the question is that we can estimate the value of one variable with the help of another known variable only if they are **correlated**.

**Hint**: Summarize your findings by stating the relationship between the two variables.

### Final Answer:
The correct answer is **correlated**.