CA Foundation P3 · Chapter 17 · Question 2 of 9
If Cov(x, y) = 18, σx = 4 and σy = 6, the coefficient of correlation is:
Test yourself: pick an answer
Reveal answer & explanation
Correct answer: D) 0.75
Explanation
r = Cov(x, y)/(σx σy) = 18/(4 x 6) = 18/24 = 0.75. Inverting the ratio gives 1.33, which is impossible since |r| cannot exceed 1.
More Correlation and Regression MCQs
- Q4For 6 pairs of ranks, the sum of squares of rank differences Σd² = 14. Spearman's rank correlation coefficient is (to two decimals):
- Q5The two regression lines are 3x + 2y = 26 and 6x + y = 31. The means of x and y are:
- Q6The two regression lines are 3x + 2y = 26 and 6x + y = 31. The coefficient of correlation between x and y is:
- Q7The coefficient of correlation from 25 pairs of observations is 0.8. Taking PE = 0.6745 x (1 − r²)/√n, the probable error of r is (to four…
- 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: