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Chapter: Linear Regression· Mathematics & Statistics (Commerce) Part 2

For a bivariate data \(\bar{x} = 10,\ \bar{y} = 12,\ V(X) = 9,\ \sigma_y = 4\) and \(r = 0.6\). Estimate \(y\) when \(x = 5\)Solution : Line of regression of Y on X is \(Y - \bar{y} = \square\,(X - \bar{x})\)\(\therefore Y - 12 = r\cdot\dfrac{\sigma_…

Q.6 (C)(i)

For a bivariate data \(\bar{x} = 10,\ \bar{y} = 12,\ V(X) = 9,\ \sigma_y = 4\) and \(r = 0.6\). Estimate \(y\) when \(x = 5\)

Solution : Line of regression of Y on X is \(Y - \bar{y} = \square\,(X - \bar{x})\)

\(\therefore Y - 12 = r\cdot\dfrac{\sigma_y}{\sigma_x}(X - 10)\)

\(\therefore Y - 12 = 0.6 \times \dfrac{4}{\square}(X - 10)\)

\(\therefore\) When \(x = 5\): \(Y - 12 = \square\,(5 - 10)\)

\(\therefore Y - 12 = -4\)

\(\therefore Y = \square\)

1 answer

Best answer

Answer: the boxes are \(b_{yx}\); \(3\); \(0.8\); \(8\). Estimated \(y = 8\) when \(x = 5\).

Line of regression of Y on X: \(Y - \bar{y} = b_{yx}(X - \bar{x})\), with \(b_{yx} = r\dfrac{\sigma_y}{\sigma_x}\).

\(\sigma_x = \sqrt{V(X)} = \sqrt{9} = 3\), so \(b_{yx} = 0.6 \times \dfrac{4}{3} = 0.8\).

\(Y - 12 = 0.8(X - 10)\). When \(x = 5\): \(Y - 12 = 0.8(5 - 10) = -4\), so \(Y = 8\).

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