Calculate the labor efficiency variance:

Labor costs:

Budgeted costs $($per unit$)2\mathrm{.}25$ hours at $16\mathrm{.}40$ per hour based on $350$ units.

Actual:

Units: $310$

Hours: $620$

Labor cost: $10,540$

a$.1,435$ favourable

b$.1,271$ favourable

c$.899$ favourable

d$.1,435$ adverse