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Broccoll Company's total overhead costs vary considerably, from month to month, based on direct labor hours. Their overhead costs consist of indirect labor, supervisor's salary and maintenance. A breakdown of these costs, for the month of October (their low month of activity), follows. Required: 1) How much of the December overhead costs (their high month of activity) are maintenance? 2) Using the high-low method, estimate the cost formula for maintenance. 3) Using the high-low method, estimate the cost formula for total overhead. 4) What total overhead costs would you expect at 3,500 labor hours