Problem:
A schedule of machinery owned by Red Bird Manufacturing Company is as follows:
Total Estimated Cost: Machine A: $450,000, Machine B, $170,000, Mach C $40,000
Estimated Salvage Value: Mach A: $30,000, Mach B: $10,000, Mach C: $0
Life in Years: Mach A: 6, Mach B: 8, Mach C: 4
Red Bird computes composite depreciation on the straight-line method. What is the "composite life" of these assets?