For two variables and , if , , then find the value of .
For two variables $x$ and $y$, if $\sigma_x = 5$, $r = \frac{-1}{2}$, $b_{yx} = \frac{-2}{7}$ then find the value of $\sigma_y$.
Answer
Answer
AIWritten by AI (gemini-2.5-pro) - it can contain mistakes.
We know that $b_{yx} = r \frac{\sigma_y}{\sigma_x}$.
Given $\sigma_x = 5$, $r = -\frac{1}{2}$, and $b_{yx} = -\frac{2}{7}$:
$-\frac{2}{7} = \left(-\frac{1}{2}\right) \frac{\sigma_y}{5} \implies \frac{2}{7} = \frac{\sigma_y}{10} \implies \sigma_y = \frac{20}{7}$.
From ISC 2026 Mathematics Paper 1, question 19(iv).