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The probability density function of the length of a metal rod is \(f(x)=2\) for \(2.3

Short Answer

Expert verified
(a) 10% of rods fail to meet specifications. (b) Center the density at 2.5 meters.

Step by step solution

01

Understanding the Range

Given the probability density function (pdf) is \( f(x) = 2 \) for \( 2.3 < x < 2.8 \). This means the total range covered by the pdf is 0.5 meters since \( 2.8 - 2.3 = 0.5 \) meters.
02

Calculating Proportion Failing the Specification

The specifications are from 2.25 to 2.75 meters. So rods with length outside this range fail to meet specifications. We need to calculate the probability of \( x < 2.25 \) and \( x > 2.75 \) within the defined pdf range (2.3 to 2.8 meters).
03

Determine Overlapping Range for Failure

For rods that are less than 2.25 meters, since \( 2.3 \) is the smallest, none can be less than 2.25. For rods greater than 2.75 meters, the range \( 2.75 < x < 2.8 \) represents failing rods. This range is 0.05 meters \((2.8 - 2.75 = 0.05)\).
04

Calculate Failing Proportion

The proportion of rods failing is the area under the pdf from 2.75 to 2.8. This is given by \( f(x) \times \text{range length} = 2 \times 0.05 = 0.1 \). Thus, 10% of rods fail to meet specifications.
05

Optimal Density Centering

To achieve the greatest proportion of bars within specifications from 2.25 to 2.75 meters with an interval of 0.5 meters, the center should be in the middle of this interval. The middle point is \((2.25 + 2.75)/2 = 2.5 \).
06

Conclusion for Centering

Center the density over 2.5 meters such that it covers \(2.25\) to \(2.75\). This ensures the maximum proportion within specification since the entire range matches the specification limits.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Specification Compliance
Specification compliance refers to whether or not the metal rods meet required length criteria. The specifications given are a range from 2.25 meters to 2.75 meters. Any rod that falls within this range is considered compliant; others are not.
To determine compliance, check where the lengths deviate from this set range.
The probability density function (pdf) provides a measure of how lengths are distributed. If part of this distribution falls outside the specified range, those are the proportions of rods that do not meet specifications.
This is crucial in manufacturing processes where precision and accuracy are vital. Ensuring compliance helps maintain quality and customer satisfaction.
Centering Interval
Centering interval involves determining the optimal range for the probability density function to maximize specification compliance.
In this exercise, the pdf covers a 0.5 meter interval. It's important to align this interval to maximize the number of rods within the desired specification limits. An optimal center would fully cover the specification range without overshooting.
For this particular case, by centering the density function over 2.5 meters, the entire range from 2.25 to 2.75 meters falls within the 0.5 meter pdf interval. This alignment leads to maximizing the compliance, as the entire density aligns perfectly within the specification limits, thereby optimizing the production yield.
Metal Rods Length Distribution
The distribution of the metal rods' lengths is represented by a probability density function, given as constant over a specified interval in this problem.
A pdf describes how probabilities are distributed along different outcomes, in this case, the length of rods. For a uniform distribution, like in this exercise, the pdf is flat, indicating equal likelihood across the interval.
For our interval of 0.5 meters (from 2.3 to 2.8), every rod's length is equally likely to be anywhere in that range. This assumption simplifies calculations, as the area under the curve is easily determined.
Such distributions help predict how many rods will meet different criterias, aiding in quality control and production forecasting.
Probability Calculation
To calculate failure probability, you need to consider the lengths that fall outside the specification range.
The calculation uses the pdf value multiplied by the "failure" range length. In this case, those rods longer than 2.75 meters contribute to the failing proportion.
This is because 2.3 meters is the lowest value of the given interval, and none can be shorter than the specification minimum of 2.25. The overlapping range of 0.05 meters (from 2.75 to 2.8) is critical.
The pdf value, 2, multiplied by this range gives a failure rate of 0.1, or 10%. Understanding this process helps refine quality assessment and improve compliance strategies.

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