Question

Scheduled maintenance should be performed in accordance with the?

1) Manufacturer's suggested procedures
2) Stipulations in 14 CFR Part 43
3) Contractor requirements

Answer 1

To assess if 1.1 hours per technician is enough, a confidence interval should be calculated using the given statistics of a mean service time of one hour, a standard deviation of one hour, and a sample size of 70 units. Budgeting only a 10% increase in time could be insufficient and may lead to an overbooked schedule for technicians.

Step-by-step explanation:

To determine whether an average of 1.1 hours per technician is sufficient for servicing air conditioners, we need to apply the concept of confidence intervals in statistics to our sample data. Given the average time of one hour with a standard deviation of one hour, and a sample size of 70 units, we can calculate the standard error of the mean (SEM) by dividing the standard deviation by the square root of the sample size.

The formula for SEM is: SEM = standard deviation / sqrt(sample size)

Which in this case gives us: SEM = 1 / sqrt(70)
After calculating the SEM, we can establish a confidence interval around the mean to predict the average time needed per technician. Utilizing a 95% confidence level, commonly used in statistical analysis, we can determine if the planned 1.1 hours falls within this interval. If it does, the company can be reasonably sure that the allotted time will be sufficient.

However, considering that budgeting only a 10% increase in time (from 1 hour average to 1.1 hours) might not adequately account for variance and unforeseen issues, especially since the standard deviation is equal to the mean itself, indicating a wide spread in the data. Therefore, budgeting for only 1.1 hours per service might be risky and lead to technicians being overbooked.

Answer 2

To determine if 1.1 hours per technician is enough for servicing air conditioners based on records with an average of one hour and a standard deviation of one hour, we use the Central Limit Theorem and calculate a confidence interval around the mean. If 1.1 hours is within the high end of this interval, it should be sufficient; otherwise, it may not be.

The corect option is 2.

Step-by-step explanation:

The question revolves around the field of statistics, specifically in estimating the time required for preventive maintenance tasks based on past service records. The scenario involves the average time and standard deviation for servicing air conditioning units, which are one hour and one hour respectively.

To determine whether budgeting an average of 1.1 hours per technician will be enough to service a sample of 70 units, the concept of the Central Limit Theorem can be used. This theorem states that the sampling distribution of the sample mean will be normally distributed if the sample size is large enough.

In this case, because the sample size is 70, which is greater than 30, we can assume the distribution of the sample mean will be approximately normal.

To calculate a confidence interval around the mean to see if 1.1 hours is sufficient, we will have to use the formula for the standard error (SE = standard deviation / sqrt(sample size)), which for this example would be 1 / sqrt(70). Then, we can find the z-score corresponding to the desired confidence level.

Assuming we want a 95% confidence interval, we would use a z-score of approximately 1.96. We multiply the SE by the z-score to find the margin of error and add/subtract it from the sample mean to get the confidence interval.

Considering the sample mean is the average time of 1 hour, a calculation would show if 1.1 hours falls within our interval. Without performing specific calculations here, we can only say generally that if the high end of the confidence interval is at or above 1.1 hours, then there should be enough time budgeted per technician. If the high end is below 1.1 hours, the time may be insufficient.

The corect option is 2.