The yield V (in millions of cubic feet per acre) for a stand of timber at age t isV = 6.8e^(-4.85)/twhere t is measured in years.(a) Find the limiting volume of wood per acre as t approaches infinity.million ft³/acre(b) Find the rates at which the yield is changing when t = 40 and t = 50. (Round your answers to three decimal places.)when t 40 years million ft³/acre/yrwhen t= 50 years million ft³/acre/yr