Is this homework? This is against the policy, as you are only cheating yourself
So let us work through this together. The answer I worked out is (show me your working, I will tell you), analysing the information.
‘The maximum power that can be obtained from a wind turbine is proportional to the cube of the wind speed.’
Assign variables: maximum power = p, wind speed = s
p = ks^3
Where k is the constant of proportionality
You should now have the information to answer the question