A slab of meat with the dimensions $20$cm $15$cm $10$cm$,$ is to be frozen between refrigerated plates with the plate temperature at $-34$ C$.$ The meat is packaged is cardboard $1\mathrm{.}5$mm thick on either side of the slab. Using Plank's equation calculate the freezing time $($ in second$)$ if the cardboard were present on the slab. Assume that for the plate freezen, the surface heat$-$transfer coefficient is $600$ j$($ m$.$sC$).$ The thermal conductivity of csrdboard is $0\mathrm{.}06$ j$($m$.$s$.$C$)$ ts latent heat of frozen is $256$ kj$/$kg water and the density is $1090$ kg$/$m$.$ The meat contains $75\%$ moisture. Assume also that meat freezes at $-2$C$.$ P$=0\mathrm{.}24$ R$=0\mathrm{.}065$