solve in 60 mins I will thumb up

Question #3: (25 Marks) A flat slab of wood 7cm thick containing 40wt% moisture is being dried from both sides (drying on other sides and edges is neglected). Hot air flows over both sides of the slab, and the equilibrium moisture at the wood surface due to is held at 8wt%. The wood piece may be considered as a semi-infinite slab. The diffusivity of the moisture in the wood is 3.72x10-2cm/h. Page 1 of 2 a) Calculate the time for the centre to reach 29.91 wt% and 10 wt% b) Determine the fluxes in a) (specify the unit). Note: wt%=1g water/100g of dry wood