Question

n=5, ∑x= ∑y=20, ∑x^2 = ∑y^2=90, ∑xy=73 then covariance (x, y) = ?​

Answer 1

cov(x,y)=73-(20/4)(20/4)

=73-25=48

Answer 2

Answer:

Covariance (x, y)  is equal to  1.4

Step-by-step explanation:

Explanation:

Given , n = 5 , ∑x = ∑y = 20 , ∑$x^2$ = ∑$y^2$ = 90  and ∑xy = 73

Covariance - A measure of the link between two random variables and how much they fluctuate together is called covariance.

Formula of covariance (x, y) = $\frac{\sum{xy}}{n} - \frac{\sum{x}}{n} \frac{\sum{y}}{n}$

This can be written as ,

Covariance(x,y) = $\frac{n\sum{xy}- \sum(x)\sum{y}}{n^2}$

Step 1:

From the question we have  ,

n = 5 , ∑x = ∑y = 20 and ∑xy = 73

Put the given value in the covariance formula ,

Covariance (x, y) = $\frac{n\sum{xy}- \sum(x)\sum{y}}{n^2}$

⇒ Covariance (x,y) = $\frac{5 (73) - 20 (20)}{5^2}$ = $\frac{-35}{25}$ = 1.4

Final answer:

Hence , 1.4 is  the value of covariance (x, y) .

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