Value 400 Points: Problem 7, 7a Worker Machine Operation Was ✓ Solved
value400 Pointsproblem 7 7a Worker Machine Operation Was Found To
Problem 7-7 A worker-machine operation was found to involve 3.6 minutes of machine time per cycle in the course of 40 cycles of stopwatch study. The worker’s time averaged 1.8 minutes per cycle, and the worker was given a rating of 120 percent (machine rating is 100 percent). Midway through the study, the worker took a 10-minute rest break. Assuming an allowance factor of 15 percent of work time which is applied only to the worker element (not the machine element), determine the standard time for this job. (Do not round intermediate calculations. Round your final answer to 2 decimal places.) Standard time minutes
Sample Paper For Above instruction
Introduction
Work measurement is a fundamental aspect of industrial engineering aimed at establishing standard times and improving productivity. Accurate determination of the standard time for a job involves considering observed times, worker ratings, allowances, and other factors like breaks. This paper calculates the standard time for a specific machine-worker operation based on provided data, applying work measurement principles to ensure precise and fair time standards.
Data Summary
- Machine time per cycle: 3.6 minutes
- Worker’s average time per cycle: 1.8 minutes
- Number of cycles observed: 40
- Worker rating: 120% (or 1.20)
- Break time taken midway: 10 minutes
- Allowance factor: 15%
- Machine rating: 100%
Analysis and Calculations
To determine the standard time, we start with the basic observed time for the worker and adjust for rating, allowances, and machine performance. The process involves several steps to account for these factors accurately.
Step 1: Calculate Actual Worker Time per Cycle
The average worker time per cycle as observed is 1.8 minutes. Since the worker was rated at 120%, this suggests that the worker's observed time needs adjustment to reflect standard performance.
Step 2: Adjust for Worker Rating
The rated time (or normal time) for the worker before allowances is calculated as:
Normal worker time per cycle = Observed worker time / Worker rating
= 1.8 minutes / 1.20 = 1.5 minutes
This represents the time the worker should take at standard pace, not accounting for allowances or breaks.
Step 3: Add Break Time and Adjust for Allowances
The worker took a 10-minute break midway during the total observation period. The total observed time for the cycles is:
Total worker observed time = 1.8 minutes per cycle × 40 cycles = 72 minutes
Note: The break occurred midway and thus reduces the total effective work time. The break's impact is to increase the total standard time because it is an unavoidable delay.
Allowance factor of 15% is applied only to the worker element, so the allowance is calculated on the normal worker time:
Allowances = 1.5 minutes × 0.15 = 0.225 minutes
Adding the allowances to the normal worker time gives:
Worker standard time per cycle = 1.5 minutes + 0.225 minutes = 1.725 minutes
Step 4: Adjust for Breaks and Calculate Total Standard Time
The 10-minute break affects the total work duration. To include this in the standard time, we consider the period in relation to the total cycles and observed time.
Since the total observed time for the worker was 72 minutes over 40 cycles, the average actual worker time per cycle, including the break effect, is 1.8 minutes. To be precise, the break effectively reduces productive work time, so we add it to the total time and then distribute across cycles.
Total effective work time including break = 72 minutes + 10 minutes = 82 minutes
However, because the break is midway, we need to adjust the entire process accordingly. For simplicity and standard practice, the standard time calculation accounts for the break by increasing the normal worker time proportionally.
Given the break occurred during the total period, the total standard time for all cycles considering the break and allowances is calculated as:
Total standard time for 40 cycles = 1.725 minutes per cycle × 40 cycles = 69 minutes
Adding the break time proportionally, we assume the break accounts for 10 minutes — so the total standard time, including rest, is:
Standard time = 69 minutes + 10 minutes = 79 minutes
This comprehensive method ensures the break is incorporated into the overall standard time.
Final Calculation and Result
Thus, the standard time for this job, rounded to two decimal places, is 79.00 minutes. This value reflects the total time necessary for a worker at standard performance, including allowances and rest period, to complete the job under typical working conditions.
Conclusion
Accurately calculating standard time involves adjustments for worker performance, allowances, and breaks. In this case, the computed standard time of 79.00 minutes provides a fair, realistic benchmark for the operation, supporting productivity planning and resource allocation.
References
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