$2\mathrm{.}6$ Leza Ltd manufactures a popular beverage in the Drakensburg region. The company was established in the $1970$s$.$ You have been appointed as the Junior Cost Accountant and the first task that has been assigned to you by the Senior Accountant is to analyse the costs. The direct materials and direct labour that has been used has amounted to R$1200000$ and R$800000$ respectively. Factory overheads have been calculated at R$300000$ for the period concerned. The office, and selling and distribution departments incurred a cost of R$450000.$ Below you are provided with information relating to the different volumes of production over the past few months.

$\backslash$table$[[$Month$,$Production volume,Overhead costs$],[$July$,300000,$R$355000],[$August$,330000,$R$385000],[$September$,290000,$R$345000],[$October$,250000,$R$305000],[$November$,400000,$R$455000],[$December$,750000,$R$805000]]$

Required:

$($a$)$ Calculate the following:

$($i$)$ The prime cost

$($ii$)$ The conversion cost

$($iii$)$ The product cost

$($iv$)$ The period cost.

$($b$)$ Calculate the following using the high$-$low method:

$($i$)$ The fixed overhead cost for the month and the variable cost per unit

$($ii$)$ The total cost of producing $500000$ units

$($iii$)$ The total cost of producing $100000$ units.