10.25 Peter Rourke, a loan processor at Wentworth Bank, has been timed performing four work elements, with the results shown in the following table. The allowances for tasks such as this are personal, 7%; fatigue, 10%; and delay, 3%.10.29 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.
Element Observations (Seconds) "Performance
Rating (%)"
1 2 3 4 5 
Grasp and place bag 8 9 8 11 7 110
Fill bag 36 41 39 35 122a 85
Seal bag 15 17 13 20 18 105
Place bag on conveyor 8 6 9 30b 35b 90
a) Compute the standard time for the bag-packing task. 
b) How many observations are necessary for 99% confidence, within ± 5% accuracy?

E3 If Professor Laurie Macdonald takes 15 minutes to grade the first exam and follows an 80% learning curve, how long will it take her: a) to grade the 25th exam? 
b) to grade the first 10 exams?

E5 Beth Zion Hospital has received initial certification from the state of California to become a center for liver transplants. The hospital, however, must complete its first 18 transplants under great scrutiny and at no cost to the patients. The very first transplant, just completed, required 30 hours. On the basis of research at the hospital, Beth Zion estimates that it will have an 80% learning curve. Estimate the time it will take to complete:
a) the 5th liver transplant. 
b) all of the first 5 transplants.
c) the 18th transplant.
d) all 18 transplants

E6 Refer to Problem E.5. Beth Zion Hospital has just been informed that only the first 10 transplants must be performed at the hospital's expense. The cost per hour of surgery is estimated to be $5,000. Again, the learning rate is 80% and the first surgery took 30 hours. a) How long will the 10th surgery take?
b) How much will the 10th surgery cost?
c) How much will all 10 cost the hospital?