The amount of energy produced by a particular wind turbine over a certain period of time can be modelled by the function E=6.289(1.28) where E is the amount of energy produced, in gigawatt-hours (GWh), after x number of years. 12. The time that it will take to produce over 20 GWh of energy, to the nearest tenth of a year, is years. (Record your answer in the numerical-response section below.)