Management wants to estimate overhead costs to plan its operations. A recent trade publication revealed that overhead costs tend to vary with machine-hours. To check this, they collected the following data for the past 12 months: Machine Overhead Month Hours Costs 1 175 $4,500 2 170 $4,225 3 160 $3,780 4 190 $5,250 5 175 $4,800 6 200 $5,100 7 160 $4,450 8 150 $3,950 9 210 $5,475 10 180 $4,760 11 170 $4,325 12 145 $3,975 Using the high-low method, what is the estimated fixed overhead costs? $628 $456 $138 $556