6. The standard time is to be established for a welding task by direct time study. The observed time for the cycle averaged 4.8 min. The worker's performance was rated at 90% on all cycles observed. After 8 cycles, the worker needed to exchange parts, which took 1.6 min, rated at 120%. Additionally, each welder is granted a 13% allowance for personal needs, fatigue, and routine delays. (Note: please refer to the corresponding course material for formulas and appropriately apply them here.) a) Determine the normal time and standard time. (4 points) b) List 2 potential causes of variability in the observed work element times that occur from cycle to cycle. (2 points) c) When would you choose to use a predetermined motion time standard over the direct time study used there? (1 points)