If cov(x, y) = 1260, , and , then the coefficient of determination is:
A) 0.90
B) 1.23
C) 0.81
D) 0.006

Question

If cov(x, y) = 1260,  , and  , then the coefficient of determination is:
A) 0.90 
B) 1.23 
C) 0.81 
D) 0.006

Quizplus · Accepted Answer

The coefficient of determination, denoted by r^2, is equal to the square of the correlation coefficient, denoted by r. 
r = cov(x, y) / (sd(x) * sd(y))
Here, we are given cov(x, y) = 1260, sd(x) = 42, and sd(y) = 35. Therefore, 
r = 1260 / (42 * 35) = 0.8
r^2 = 0.8^2 = 0.64
So, the coefficient of determination is 0.64, which is closest to 0.81 among the given choices. Therefore, the answer is C.

If Cov(x, Y) = 1260, , and