The Dubuque Cement Company packs 80-pound bags of concrete mix. Time-study data for the filling activity are shown in the following table. Because of the high physical demands of the job, the company's policy is a 23% allowance for workers.a) Compute the standard time for the bag-packing task.

b) How many observations are necessary for 99% confidence, within 5% accuracy?

Observations (seconds) Performance

Element 1 2 3 4 5 Rating (%)

Grasp and place bag 8 9 8 11 7 110

Fill bag 36 41 39 35 112a 85

Seal bag 15 17 13 20 18 105

Place bag on conveyor 8 6 9 30b 35b 90

aBag breaks open; included as delay in the allowance factor.
bConveyor jams; included as delay in the allowance factor