Month

July August September October November December

Service hours $116132256422322326$

Revenue $ $6,496$ $ $7,392$ $ $14,336$ $ $23,632$ $ $18,032$ $ $18,256$

Operating costs $ $4,240$ $ $5,220$ $ $7,170$ $ $11,130$ $ $9,180$ $ $10,570$

Use the high$-$low method to estimate the total monthly fixed cost and the variable cost per hour.

Determine the average contribution margin per hour.