a) Installing mufflers at the O'Sullivan Garage in Golden, Colorado, involves five work elements. Jill O'Sullivan has timed workers performing these tasks seven times, with the results shown in the following table.

b) The number of observations that are required for a 90% confidence level within 5% accuracy = ___ observations (round your response to the immediate higher whole number).

Element Select correct muffler Remove old muffler Weld/install new muffler Check/inspect work Complete paperwork Performance Rating 110% 85% 100% 105% 135% 1 3 6 14 3 4 2 6 8 14 3 6 Observation (minutes) 3 5 8 13 23 8 4 7 7 11 5 5 4 7 15 4 7 6 16 6 17 4 6 7 4 6 12 17 6 Employee has lengthy conversations with boss (not job related) By agreement with her workers, Jill allows a 14% fatigue factor and a 12% personal-time factor. To compute the standard time for the work operation, Jill excludes all observations that appear to be unusual or nonrecurring. She does not want an error more than 5%. (Round all intermediate calculations to two decimal places before proceeding with further