Electrical costs at one of Rome Corporation's factories are listed below. March April May June July August September October November Machine-Hours Electrical Cost 458 1,007 423 934 440 979 409 982 426 952 372 822 414 926 431 949 468 1,025 Management believes that electrical cost is a mixed cost that depends on machine-hours. Using the high-low method, the estimate of the variable component of electrical cost per machine-hour is closest to