Consider the following data for four SKUs that you will store in a block$-$stacking pallet storage system, where qi is the received order quantity for SKU i and zi is the stack height $($in pallets$)$ of SKU i:

SKU

qi

zi

A

$26$

$3$

B

$27$

$2$

C

$12$

$1$

D

$25$

$4$

Suppose aisles are $12$ feet wide, pallets are $48\backslash$times $40$ inches $(40$ is the width$),$ and there is a $1-$foot gap between stacks.

What is the optimal $($non$-$integer$)$ value for the lane depth?