a)
To determine: The normal time for the operation
Introduction: Time study is the basis that helps set the standard time; it would time a sample of the performance of the worker.
a)
Answer to Problem 25P
Thenormal time calculated as 3.23 minutes.
Explanation of Solution
Given information:
The allowance for tasks is given as 7% for personal, 10% for fatigue, and 3% for delay. The observed time and performance rating for each element is given as follows:
Element | Performance rating | Observation (minutes per cycle) | ||||
1 | 2 | 3 | 4 | 5 | ||
1 | 110% | 0.5 | 0.4 | 0.6 | 0.4 | 0.4 |
2 | 95% | 0.6 | 0.8 | 0.7 | 0.6 | 0.7 |
3 | 90% | 0.6 | 0.4 | 0.7 | 0.5 | 0.5 |
4 | 85% | 1.5 | 1.8 | 2 | 1.7 | 1.5 |
Formulae to calculate normal time:
Calculate the normal time:
Element | Performance rating | Observation (minutes) | Average time | Normal time | ||||
1 | 2 | 3 | 4 | 5 | ||||
1 | 110% | 0.5 | 0.4 | 0.6 | 0.4 | 0.4 | 0.46 | 0.51 |
2 | 95% | 0.6 | 0.8 | 0.7 | 0.6 | 0.7 | 0.68 | 0.65 |
3 | 90% | 0.6 | 0.4 | 0.7 | 0.5 | 0.5 | 0.54 | 0.49 |
4 | 85% | 1.5 | 1.8 | 2 | 1.7 | 1.5 | 1.7 | 1.45 |
Excel worksheet:
Calculate the average time for the first element:
The average time is calculated by taking an average of the observation given, which is summation of 0.5, 0.4, 0.6, 0.4, and 0.4 and dividing the result by 5. Hence, the average is 0.46 minutes.
Calculate the average time for the second element:
The average time is calculated by taking an average of the observation given, which is summation of 0.6, 0.8, 0.7, 0.6, and 0.7 and dividing the result by 5. Hence, the average is 0.68 minutes.
Calculate the average time for the third element:
The average time is calculated by taking an average of the observation given, which is summation of 0.6, 0.4, 0.7 0.5, and 0.5 and dividing the result by 5. Hence, the average is 0.54 minutes.
Calculate the average time for the fourth element:
The average time is calculated by taking an average of the observation given, which is summation of 1.5, 1.8, 2.0, 1.7, and 1.5 and dividing the result by 5. Hence, the average is 1.7 minutes.
Calculate the normal time for the first element:
The normal time is calculated by multiplying the average time and performance rating. The average time is calculated as 0.46 minutes, and performance rating is given as 110%. Hence, the normal time is 0.51 minutes.
Calculate the normal time for the second element:
The normal time is calculated by multiplying the average time and performance rating. The average time is calculated as 0.68 minutes, and performance rating is given as 95%. Hence, the normal time is 0.65 minutes.
Calculate the normal time for the third element:
The normal time is calculated by multiplying the average time and performance rating. The average time is calculated as 0.54 minutes, and performance rating is given as 90%. Hence, the normal time is 0.49 minutes.
Calculate the normal time for the fourth element:
The normal time is calculated by multiplying the average time and performance rating. The average time is calculated as 1.7 minutes, and performance rating is given as 85%. Hence, the normal time is 1.45 minutes.
Calculate the total normal time:
The normal time is calculated by adding the normal time of all the elements.
Hence, the total normal time is 3.08 minutes.
b)
To determine: The standard time for the operation.
Introduction: Time study is the basis that helps set the standard time, it would time a sample of the performance of the worker.
b)
Answer to Problem 25P
Thestandard time is calculated as 5.4 minutes.
Explanation of Solution
Given information:
The allowance for tasks is given as 7% for personal, 10% for fatigue, and 3% for delay. The observed time and performance rating for each element are given as follows:
Element | Performance rating | Observation (minutes per cycle) | ||||
1 | 2 | 3 | 4 | 5 | ||
1 | 110% | 0.5 | 0.4 | 0.6 | 0.4 | 0.4 |
2 | 95% | 0.6 | 0.8 | 0.7 | 0.6 | 0.7 |
3 | 90% | 0.6 | 0.4 | 0.7 | 0.5 | 0.5 |
4 | 85% | 1.5 | 1.8 | 2 | 1.7 | 1.5 |
Formulae to calculate standard time:
Calculate the allowance factor:
The allowance factor is calculated by adding personal allowance, fatigue, and delay allowance. Personal allowance is given as 7%, fatigue is 10%, and delay allowance is 3%. Hence, the allowance factor is 20%.
Calculate the standard time:
The standard time is calculated by dividing the normal time with the value attained by subtracting the allowance factor from 1. The normal time is calculated as 3.08 minutes and the allowance factor is calculated as 20%
Hence, the standard time is 3.85 minutes.
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Chapter 10 Solutions
Principles Of Operations Management
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