Answer:
Knowing we only have one load applied in just one direction we have to use the Hooke's law for one dimension
ex = бx/E
бx = Fx/A = Fx/π
Using both equation and solving for the modulus of elasticity E
E = бx/ex = Fx / π
ex
E = 
Apply the Hooke's law for either y or z direction (circle will change in every direction) we can find the change in radius
ey =
(бy - v (бx + бz)) =
бx
=
= 
Finally
ey = Δr / r
Δr = ey * r = 10 * 
Δd = 2Δr = 
Explanation:
The average power is 10 watts. What's the question ?
I don’t think you can :((
They do the method 3 times to be sure. Because if you do it once, that could mean anything. If you do it twice, it may or may not have the same result. If you do it 3 times and it matches one of the previous answers, then it's likely that it's correct.