$5\mathrm{.}11$ Foral Ltd$,$ which distributes electrical products in the UK$,$ plans to build a new warehouse to accommodate $60000$ palletized unit

loads. Goods will be stocked on selective racks and handled by means of forklift trucks. Each rack will have five tiers, each of which can

store up to five palletized unit loads. Racks will be arranged as in Figure $5\mathrm{.}89,$ where vertical aisles are $1\mathrm{.}5m$ wide, while the horizontal

aisles are $2\mathrm{.}5m$ wide. Each palletized unit load will require an area equal to $120\mathrm{.}080\mathrm{.}3c{m}^2($taking into account the width clearance$).$ Size the

storage zone, under the hypothesis that the probability that the picker enters the storage zone from the first I$/$O point is $p(0p1),$ whereas the

probability is $(1-$p$)$ if they enter from the second I$/$O point.

Figure $5\mathrm{.}89$ Storage zone layout in the Foral problem.