Concept explainers
a)
To determine: The standard time for the operation.
Introduction: The amount of the dependency on human effort by an organization in terms of achieving its goals is given by the work design. It is directly linked to the productivity of an organization where good work design helps in achieving high productivity.
a)
Answer to Problem 9P
Explanation of Solution
Given information:
Performance rating | Observations (minutes per cycles) | Allowance | ||||
1 | 2 | 3 | 4 | 5 | ||
0.9 | 1.4 | 1.42 | 1.39 | 1.38 | 1.41 | 0.10 |
1.2 | 2.1 | 2.05 | 2 | 1.85 | 1.8 | 0.10 |
1.11 | 1.6 | 1.4 | 1.5 | 1.45 | 1.55 | 0.10 |
Formula:
Element | Performance rating | Observations (minutes per cycles) | Allowance | Observed time | Normal time | Afjob | Standard time | ||||
1 | 2 | 3 | 4 | 5 | |||||||
A | 0.9 | 1.4 | 1.42 | 1.39 | 1.38 | 1.4 | 0.10 | 1.4 | 1.26 | 1.10 | 1.39 |
B | 1.2 | 2.1 | 2.05 | 2 | 1.85 | 1.8 | 0.10 | 1.96 | 2.352 | 1.10 | 2.59 |
C | 1.11 | 1.6 | 1.4 | 1.5 | 1.45 | 1.6 | 0.10 | 1.5 | 1.665 | 1.10 | 1.83 |
Standard time for operation | 5.80 |
Calculation of standard time of operation:
Excel Worksheet:
Element A:
Normal time is calculated by multiplying observed timing, 1.4 and performance rating, 0.9 which yields 1.26 minutes.
Allowance factor is calculated by adding 1 with the allowance factor 0.10 to give 1.10.
Standard time for element A is calculated by multiplying normal time of 1.26 minutes with allowance factor of 1.10 which gives 1.39 minutes.
Same process applies for element B and C which yields the standard times as 2.59 and 1.83. The standard time for operation is obtained by adding 1.39, 2.59 and 1.83 minutes which gives 5.80 minutes.
Hence, the standard time for the operation is 5.80 minutes.
b)
To determine: The number of observations for element A
Introduction: The amount of the dependency on human effort by an organization in terms of achieving its goals is given by the work design. It is directly linked to the productivity of an organization where good work design helps in achieving high productivity.
b)
Answer to Problem 9P
Explanation of Solution
Given information:
Performance rating | Observations (minutes per cycles) | Allowance | ||||
1 | 2 | 3 | 4 | 5 | ||
0.9 | 1.4 | 1.42 | 1.39 | 1.38 | 1.41 | 0.10 |
1.2 | 2.1 | 2.05 | 2 | 1.85 | 1.8 | 0.10 |
1.11 | 1.6 | 1.4 | 1.5 | 1.45 | 1.55 | 0.10 |
Confidence= 98%
4% of true value
Formula:
Calculation of number of observations for element A:
In the above formula the sample standard deviation is calculated by,
Calculation of standard deviation:
Element A | Differences | Square of differences | Standard deviation |
1.4 | 0 | 0 | 0.015811 |
1.42 | 0.02 | 0.0004 | |
1.39 | -0.01 | 0.0001 | |
1.38 | -0.02 | 0.0004 | |
1.41 | 0.01 | 0.0001 | |
Mean=1.4 | SSQ=0.001 |
Excel worksheet:
Z value for confidence interval of 98% is 2.33.
The confidence interval
Using z = 2.33:
The number of observations from the standard z table for confidence level of 98% is calculated by dividing the product of 2.33 and 0.0158 with product of 0.04 and 1.40 and squaring the resultant which gives 0.4322. Rounding off the value it gives the number of observation as 1.
Hence, the number of observation is 1.
c)
To determine: The number of observations for element C.
Introduction: The amount of the dependency on human effort by an organization in terms of achieving its goals is given by the work design. It is directly linked to the productivity of an organization where good work design helps in achieving high productivity.
c)
Answer to Problem 9P
Explanation of Solution
Given information:
Performance rating | Observations (minutes per cycles) | Allowance | ||||
1 | 2 | 3 | 4 | 5 | ||
0.9 | 1.4 | 1.42 | 1.39 | 1.38 | 1.41 | 0.10 |
1.2 | 2.1 | 2.05 | 2 | 1.85 | 1.8 | 0.10 |
1.11 | 1.6 | 1.4 | 1.5 | 1.45 | 1.55 | 0.10 |
Confidence= 90%
0.10 minute of actual value.
Formula:
Calculation of number of observations for element C:
In the above formula the sample standard deviation is calculated by,
Calculation of standard deviation:
Element C | Differences | Square of differences | Standard deviation |
1.6 | 0.1 | 0.01 | 0.0791 |
1.4 | -0.1 | 0.01 | |
1.5 | 0 | 0 | |
1.45 | -0.05 | 0.0025 | |
1.55 | 0.05 | 0.0025 | |
Mean=1.5 | SSQ=0.025 |
Excel worksheet:
Z value for confidence interval of 90% is 1.65.
The confidence interval
- Using z = 1.64:
The number of observations from the standard z table for confidence level of 90 is calculated by dividing the product of 1.64 and 0.0791 with 0.10 and squaring the resultant which gives 1.6828.
- Using z = 1.65:
The number of observations from the standard z table for confidence level of 90 is calculated by dividing the product of 1.65 and 0.0791 with 0.10 and squaring the resultant which gives 1.7034.
Hence, the number of observations for element C is 2
Want to see more full solutions like this?
Chapter 7 Solutions
STEVENSON: OPERATIONS MANAGEMENT(LL)
- A widget assembly process was timed for 75 cycles and had an average of 1.5 minutes per piece. The performance rating was 95%, and workday allowances are 10 percent. Determine the following: a) Observed time b) Normal time c) Standard time d) How might this information be used?arrow_forward5. The manager of Asombrado Bounty Office, Charles Badillo, estimates his employees are idle 25%of the time. With that problem, how many work samples are needed to consider within 3%accuracy and have 95.45% confidence level. 6. At ASP Micro Manufacturing, Inc. workers press semiconductor into predrilled slots on printed-circuit boards. Determine the normal time of the operation in seconds. The elemental motions for normal time used by the company are as follows:• Reach 6 inches for semiconductors 10.5 TMU• Grasp the semiconductors 8.0 TMU• Move semiconductor to printed-circuit board 9.5 TMU• Position semiconductor 20.1 TMU• Press semiconductor into slots 20.3 TMU• Move board aside 15.8 TMU 7. The semiconductor used in Costin Calculator has 5 components with the consistency of 90%, 95%,98%, 90%, and 99%, respectively. How reliable is one product of calculator?arrow_forwardUse excel to show formulas 2.A job had an observed time of five minutes, a performance rating of .70, and an allowance factor of 20 percent of job time. Twenty cycles were timed. Standard time for the job in minutes is:arrow_forward
- Identify to which category of “personal”, “fatigue”, or “delay” the following job elements belong to a) The hair-dresser takes the phone to confirm a booking, in the middle of a client haircut. b) The doctor takes a cup of coffee and a quick rest in a short time between visiting two patients. c) In a long-distance drive, the coach driver stops in a service area every two to three hours to have some food.arrow_forwardQ2 (a) A time study analyst timed an assembly operation for 30 cycles, and then computed the average time per cycle, which was 18.75 minutes. The analyst assigned a performance rating of 0.96 and decided that an appropriate allowance was 15 percent. Assume the allowance factor is based on the workday. Determine the following: (i) Observed time (OT) (ii) The Normal times (NT) (iii) The standard time (ST) (b) If the analyst wants to estimate the number of observations that will be needed to achieve a specified maximum error, with a confidence of 95.5 %. A preliminary study yielded a mean of 5.2 minutes and a standard deviation of 1.1 minutes. Determine the total number of observation needed for these two cases: (a) A maximum error of + or - 6 % (b) A maximum error of 40 minutesarrow_forwardA Methods and Measurements Analyst needs to develop a time standard for a certain task. The task involves use of a ruler, square, and portable electric saw to mark and cut the "notch" in a rafter (a standard carpentry task of home construction). In a preliminary study, he observed one of his workers performing this task five times. The observations were made in an air-conditioned, well-lit training facility, at ground level, with all tools and equipment clean and readily available. Observation: 1 2 3 4 5 Task time (seconds): 82 74 80 88 76 (a) What is the actual average time for this task? (b) What is the normal time for this task if the employee worked at a 10% faster pace than is typical for adequately trained workers? (c) What is standard time for this task if allowances sum to 12%? (d) If the analyst then thought more carefully about his experiment and decided that the allowances needed to be increased to match the real (outside, not…arrow_forward
- Susan Cottenden clocked the observed time for weld-ing a part onto truck doors at 5.3 minutes. The performance rat-ing of the worker timed was estimated at 105%. Find the normal time for this operation.Note: According to the local union contract, each welder isallowed 3 minutes of personal time per hour and 2 minutes offatigue time per hour. Further, there should be an average delayallowance of 1 minute per hour. Compute the allowance factorand then find the standard time for the welding activity.arrow_forwardA job in an insurance office involves telephone conversations with policyholders. The office manager estimates that about half of the employee’s time is spent on the telephone. How many observations are needed in a work sampling study to estimate that time percentage to within 6 percent and have a confidence of 98 percent?arrow_forwardGive at least 3 examples of jobs that requires Work Measurement and give a brief explaination.arrow_forward
- The “worker” in this scenario had to perform a candy-sorting task and the rest of the class had to record the observed times (OT) for the task. It was decided that the rating for the “worker” was 100%. Given the following table, find the standard time for each element. Write your answers in order from Element #1 --> Element #5. Answers must have one decimal place: e.g. 3.0 or 12.5. Round up if necessary. Assume a total allowance of 5%. In your equation you will use for ST, consider allowance to be 0.05. Element Trail 1 Trial 2 Standard Time 1 Walk to podium 3 sec 3 sec 2 Fill mug 5 sec 6 sec 3 Walk to desk/sit 5 sec 4 sec 4 Sort Candy 12 sec 12 sec 5 Walk to desk 4 sec 4 secarrow_forwardGiven below ratings based on skill and effort, compute for the average observed time if the normal time is 8 minutes? Skill – A1 +0.15; Effort – B1 +0.10arrow_forwardA time study was made of an existing job to develop new time standards. A worker was observed for 45 minutes.During that period, 30 units were produced. The analyst rated the worker as performing at a 90 percent performance rate. Allowances in the firm for rest and personal time are 12 percent. a. What is the normal time for the task?b. What is the standard time for the task?c. If the worker produced 300 units in an eight-hour day, what would be the day’s pay if the basic rate was $6 per hour and the premium payment system paid on a 100 percent basis?arrow_forward
- Practical Management ScienceOperations ManagementISBN:9781337406659Author:WINSTON, Wayne L.Publisher:Cengage,Operations ManagementOperations ManagementISBN:9781259667473Author:William J StevensonPublisher:McGraw-Hill EducationOperations and Supply Chain Management (Mcgraw-hi...Operations ManagementISBN:9781259666100Author:F. Robert Jacobs, Richard B ChasePublisher:McGraw-Hill Education
- Purchasing and Supply Chain ManagementOperations ManagementISBN:9781285869681Author:Robert M. Monczka, Robert B. Handfield, Larry C. Giunipero, James L. PattersonPublisher:Cengage LearningProduction and Operations Analysis, Seventh Editi...Operations ManagementISBN:9781478623069Author:Steven Nahmias, Tava Lennon OlsenPublisher:Waveland Press, Inc.