E$18\mathrm{.}5($LO $1,2),$ AP The controller of Hall Industries has collected the following monthly cost data for use in analyzing the behavior of maintenance costs.

$\backslash$table$[[$Month$,\backslash$table$[[$Total$],[$Maintenance Costs$]],\backslash$table$[[$Total$],[$Machine Hours$]]],[$January$,$$$2,640,3,500],[$February$,3,000,4,000],[$March$,3,600,6,000],[$April$,4,500,7,900],[$May$,3,200,5,000],[$June$,4,620,8,000]]$

Instructions

a$.$ Determine the fixed costs and unit variable costs using the high$-$low method for this mixed cost.

b$.$ Prepare a graph showing the behavior of maintenance costs and identify the fixed$-$cost and variable$-$cost components. Use $2,000-$hour increments and $$1,000-$cost increments.