Recent maintenance costs of Divers Corporation are listed below: 527 February March April May June July August September Machine-Hours Maintenance Costs 5,144 499 5,033 542 5,220 541 5,196 4,973 543 5,200 5,288 5,860 489 558 Management believes that maintenance cost is a mixed cost that depends on machine-hours. Using the least-squares regression method, the estimate of the fixed component of maintenance cost per month is closest to