Answer:
$1.9 per MH
Explanation:
Since the associated rate variance is unfavorable, that amount must be subtracted from the actual maintenance cost in order to obtain the standard maintenance cost (SMC):
[tex]SMC = \$12,550 - \$390\\SMC = \$12,160[/tex]
During July, 6,400 machine-hours were actually worked, so the standard maintenance cost per machine-hour was:
[tex]\frac{\$12,160}{6,400} = \$1.9[/tex]
The cost was $1.9 per MH