CA Foundation P3 · Chapter 17 · Question 6 of 9
The two regression lines are 3x + 2y = 26 and 6x + y = 31. The coefficient of correlation between x and y is:
Test yourself: pick an answer
Reveal answer & explanation
Correct answer: B) −0.5
Explanation
Assume 3x + 2y = 26 is y on x: y = 13 − 1.5x, so byx = −1.5. Then 6x + y = 31 is x on y: x = 31/6 − y/6, so bxy = −1/6. The product 0.25 ≤ 1, so the assumption is valid (the reverse gives a product of 4, which is impossible). r = −√0.25 = −0.5, negative because both coefficients are negative.
More Correlation and Regression MCQs
- Q8Given x̄ = 20, ȳ = 45 and the regression coefficient of y on x, byx = 1.2, the estimated value of y when x = 25 is:
- Q9When the coefficient of correlation r = 0, the two lines of regression are:
- Q1The coefficient of correlation r always lies between:
- Q2If Cov(x, y) = 18, σx = 4 and σy = 6, the coefficient of correlation is:
- Q3The two regression coefficients are byx = 0.8 and bxy = 0.45. The coefficient of correlation is: