(1) Whenever the opening of a junior high school is approved for the ensuing school fiscal year under 20-6-505, the county superintendent shall estimate the average number belonging (ANB) after investigating the probable enrollment for the junior high school. The ANB determined by the county superintendent and the ANB actually realized in subsequent school fiscal years must be applied to prorate the BASE funding program amount between the elementary and high school districts. Each district shall adopt its general fund budget on the basis of the prorated amount and shall finance its proportionate share of the cost of operating the junior high school.
(2) The cost of operating the junior high school must be prorated between the elementary district and the high school district on the basis of the ratio that the number of pupils of their district is to the total enrollment of the junior high school.