OPS MGMT Problems – 9.11, 9.13, 9.15, 9.25 and 9.29

9.11 Stanford Rosenberg Computing wants to establish an assembly line for producing a new product, the Personal Digital Assistant (PDA). The tasks, task times, and immediate predecessors for the tasks are as follows:TASK TIME (sec)IMMEDIATEPREDECESSORSA 12 —B 15 AC 8 AD 5 B, CE 20 DRosenberg’s goal is to produce 180 PDAs per hour.a) What is the cycle time?b) What is the theoretical minimum for the number of workstations that Rosenberg can achieve in this assembly line?c) Can the theoretical minimum actually be reached when workstations are assigned?9.13 Sue Helms Appliances wants to establish an assembly line to manufacture its new product, the Micro Popcorn Popper. The goal is to produce five poppers per hour. The tasks, task times, and immediate predecessors for producing one Micro Popcorn Popper are as follows:TASKTIME(min)IMMEDIATEPREDECESSORSA 10 —B 12 AC 8 A, BD 6 B, CE 6 CF 6 D, Ea) What is the theoretical minimum for the smallest number of workstations that Helms can achieve in this assembly line? b) Graph the assembly line and assign workers to workstations. Can you assign them with the theoretical minimum?c) What is the efficiency of your assignment?9.15 The following table details the tasks required for Indiana-based Frank Pianki Industries to manufacture a fully portable industrial vacuum cleaner. The times in the table are in minutes. Demand forecasts indicate a need to operate with a cycle time of 10 minutes.ACTIVITY ACTIVITY DESCRIPTIONIMMEDIATEPREDECESSORS TIMEA Attach wheels to tub — 5B Attach motor to lid — 1.5C Attach battery pack B 3D Attach safety cutoff C 4E Attach filters B 3F Attach lid to tub A, E 2G Assemble attachments — 3H Function test D, F, G 3.5I Final inspection H 2J Packing I 2a) Draw the appropriate precedence diagram for this production line.b) Assign tasks to workstations and determine how much idle time is present each cycle.c) Discuss how this balance could be improved to 100%.d) What is the theoretical minimum number of workstations 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%.TASKELEMENTPERFORMANCERATING (%)OBSERVATIONS (MINUTES)1 2 3 4 51 110 .5 .4 .6 .4 .42 95 .6 .8 .7 .6 .73 90 .6 .4 .7 .5 .54 85 1.5 1.8 2.0 1.7 1.5a) What is the normal time?b) What is the standard time?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. a) Compute the standard time for the bag-packing task.b) How many observations are necessary for 99% confidence, within {5% accuracy?ELEMENT OBSERVATIONS (SECONDS) PERFORMANCE1 2 3 4 5 RATING (%)Grasp and place bag 8 9 8 11 7 110Fill bag 36 41 39 35 112a 85Seal bag 15 17 13 20 18 105Place bag on conveyor 8 6 9 30b 35b 90 a) Bag breaks open; included as delay in the allowance factor.b) Conveyor jams; included as delay in the allowance factor.