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Do not use computer(excel or other programmes! Solution must made by handwriting.

Q11. Installing mufflers at the Stanley Garage in Golden, Colorado, involves five work elements. An engineer has timed workers performing these tasks eight times, with the results shown in the following table. Observations (minutes) 2 3 4 5 6 Job Element 1 7 1. Select correct mufflers 2. Remove old muffler 3. Weld/install new muffler 4. Check/inspect work 5. Complete paperwork Performance Rating (%) 110 90 105 100 130 4 6 15 3 5 5 8 14 4 6 4 7 14 24 8 6 6 12 5 4 7 15 4 7 15 6 16 3 6 7 7 13 18 7 By aggreement with her workers, the engineer allows a 10% fatigue factor, a 10% personal-time factor but no time for delay. To compute standard time for the work operation. She does not want an error of more than 5%. How many observations are needed to assure a 96% confidence level