If cov(x,y)= 20, $s _ { x } ^ { 2 } = 16$ and $s _ { y } ^ { 2 } = 49$ then the sample coefficient of correlation r is:
A) 1.400
B) 0.026
C) 0.714
D) None of these choices.

Question

Quizplus · Accepted Answer

The sample coefficient of correlation is given by:
$$r = \frac{cov(x,y)}{s_x s_y}$$
Substituting the given values, we get:
$$r = \frac{20}{\sqrt{16} \sqrt{49}} = \frac{20}{4 \cdot 7} = 0.714$$
Therefore, the answer is C.

If Cov(x,y)= 20 sx2=16s _ { x } ^ { 2 } = 16sx2​=16

If Cov(x,y)= 20 $s _ { x } ^ { 2 } = 16$