4 The logistic model has been applied to the natural growth of the halibut population in certain areas of the Pacific Ocean. Let x, measured in kilograms, be the total mass, or biomass, of the halibut population at time t. The parameters in the logistic equation are estimated to have the values k = 0.71/year and K = 80.5×106 kg. If the initial biomass is xo = 0.25K, find the biomass 2 years later. Also find the time t for which x (t) = 0.75K.