18.
1 answer:
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Answer:
1. Co-variance= -1.2
2. correlation coefficient= -0.4404
3. There is weak negative relationship between x and y.
Explanation:
1.
Co-variance= Cov(x,y)= sum[(x-xbar)(y-ybar)]/n
xbar=sumx/n=32/5=6.4
ybar=sumy/n=35/5=7
x 7 8 5 3 9
x-xbar 0.6 1.6 -1.4 -3.4 2.6
y 7 5 9 7 7
y-ybar 0 -2 2 0 0
(x-xbar)(y-ybar) 0 -3.2 -2.8 0 0
Cov(x,y)= sum[(x-xbar)(y-ybar)]/n=-6/5=-1.2
Cov(x,y)=-1.2
2.
correlation coefficient=r
x 7 8 5 3 9
x-xbar 0.6 1.6 -1.4 -3.4 2.6
y 7 5 9 7 7
y-ybar 0 -2 2 0 0
(x-xbar)(y-ybar) 0 -3.2 -2.8 0 0
(x-xbar)² 0.36 2.56 1.96 11.56 6.76
(y-ybar)² 0 4 4 0 0
r=-0.4404
3. Since the value of correlation coefficient is negative and less than 0.5 , so, we can say that there is weak negative relationship between x and y.