The superintendent of public instruction, pursuant to RCW
28A.310.330 shall prepare the biennial budget request for the operation of educational service districts based upon a formula using the following factors:
(1) The core service cost itemized in RCW
28A.310.350 which shall receive primary weighting for formula purposes;
(2) A weighting factor constituting a geographical factor which shall be used to weight the larger sized educational service districts for formula purposes; and
(3) A weighting factor which shall be based on the number and size of local school districts within each educational service district for formula purposes.
The sum of subsection (1) of this section, together with the weighting factors of subsections (2) and (3) of this section for each educational service district, shall reflect the variables among the educational service districts and when combined, a total budget for all educational service districts shall be the result.