The regression coefficient of y on x is `sigma_(x)//sigma_(y)`

Answer

To determine whether the statement "The regression coefficient of y on x is σ_x / σ_y" is true or false, we need to analyze the definitions and formulas related to regression coefficients and correlation.

### Step-by-Step Solution:

1. **Understand Regression Coefficient**:
The regression coefficient of y on x, often denoted as b_yx, represents the change in y for a unit change in x.

2. **Recall the Formula**:
The formula for the regression coefficient of y on x is given by:
\[ b_{yx} = r \frac{\sigma_y}{\sigma_x} \]
where:
- \( b_{yx} \) is the regression coefficient of y on x,
- \( r \) is the correlation coefficient between x and y,
- \( \sigma_y \) is the standard deviation of y,
- \( \sigma_x \) is the standard deviation of x.

3. **Analyze the Given Statement**:
The statement claims that the regression coefficient of y on x is equal to \( \frac{\sigma_x}{\sigma_y} \).

4. **Compare with the Correct Formula**:
From the formula we recalled, we see that:
\[ b_{yx} = r \frac{\sigma_y}{\sigma_x} \]
This clearly shows that the regression coefficient is not equal to \( \frac{\sigma_x}{\sigma_y} \) but rather involves the correlation coefficient and the ratio of the standard deviations.

5. **Conclusion**:
Since the statement does not match the established formula for the regression coefficient, we conclude that the statement is false.

### Final Answer:
The statement "The regression coefficient of y on x is σ_x / σ_y" is **False**.