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.
Are you asking what that is if so it would be called nuclear energy and if you want what is energy locked in the bonds of atoms that would be chemical energy