The controller of Pharoah Industries has collected the following monthly cost data for use in analyzing the behavior of maintenance costs.

$\backslash$table$[[$Month$,$Total,Total$],[$Maintenance Costs,Machine Hours,$],[$January$,$$$2,710,320],[$February$,3,010,370],[$March$,3,610,520],[$April$,4,510,670],[$May$,3,210,520],[$June$,5,710,720]]$

$($a$1)$

Determine the unit variable costs using the high$-$low method for this mixed cost. $($Round answer to $2$ decimal places e$.$g$.2\mathrm{.}25.)$

Variable cost per machine hour $