Question

Covariance $(x,y)$ between $x$ and $y$ if $\sum x=15,\sum y=40,\sum xy=110,n=5$ is

• A. $22$
• B. $2$
• C. $-2$
• D. None of these

Answer 1

Answer: (C)

$-2$

$COV(x,y)=\frac{\sum xy}{n}-\left(\frac{\sum x}{n}\right)\left(\frac{\sum y}{n}\right)$
$=\frac{110}{5}-\left(\frac{15}{5}\right)\left(\frac{40}{5}\right)=22-3\times 8=-2$
Hence choice (c) is correct answer.