Estimate total fixed costs and unit variable costs using the high-low method: Month September October November December Units produced 700 1,000 850 900 Total cost $3,400 $4,600 $4,500 $4,300 Total fixed costs: $400; Variable costs/unit: $4.35/unit Total fixed costs: $850; Variable costs/unit: $5.50/unit Total fixed costs: $600; Variable costs/unit: $4.00/unit Total fixed costs: $600; Variable costs/unit: $6.00/unit