[Solved] Four coins are flipped.Each coin tail is recorded as a 0 and a head as a 1 and the source symbol is the sum, with \(\mathrm { X } _ { 1 }\) corresponding to sum =0, \(X _ { 2 }\) to sum = 1, etc.The number of unique symbols is _______. Activity-based Costing: A costing method that assigns overhead and indirect costs to specific activities, providing more accurate product costing. Idle Capacity: The unused portion of a company's production or service potential, often resulting in inefficiencies and increased costs. Activity-Based Costing: A costing method that assigns costs to products or services based on the activities they require, aiming to provide more accurate product cost information. Machine-Hours: A unit of measure representing the operating time of a machine, used in allocating costs to products based on machine usage.