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2.4.6 WP Strands of copper wire from a manufacturer are analyzed for strength and conductivity. The results from 100 strands are as follows: Strength High Low High conductivity $$74$$ Low conductivity 15 a. If a strand is randomly selected, what is the probability that its conductivity is high and its strength is high? b. If a strand is randomly selected, what is the probability that its conductivity is low or its strength is low? c. Consider the event that a strand has low conductivity and the event that the strand has low strength. Are these two events mutually exclusive?

Short Answer

Expert verified
a) 0.74 b) 0.26 c) No, they are not mutually exclusive.

Step by step solution

01

Analyze the given table

First, examine the data provided about the strands of copper wire: - High Conductivity & High Strength = 74 strands - Low Conductivity & High Strength = 15 strands - No specific data given for the remaining categories (we'll find those in the later steps). Total strands = 100.
02

Calculate the probability of high conductivity and high strength (Part a)

To find the probability that a strand picked at random has high conductivity and high strength, divide the number of strands with both high conductivity and high strength by the total number of strands. Number of strands with high conductivity and high strength: 74.Total number of strands: 100.Probability = \( \frac{74}{100} = 0.74 \).
03

Complete the data table for remaining probabilities

To calculate the required probabilities for part b, we need to deduce the remaining counts: - Total number of low conductivity strands = 100 - 74 = 26. Because 15 are low conductivity with high strength, we calculate low conductivity with low strength. - Low Conductivity & Low Strength = 26 - 15 = 11. We now assume that the missing part of the data involves strands with high conductivity and low strength. - High Conductivity & Low Strength = 100 - (74+15+11) = 0. Now you have: - High Conductivity & High Strength = 74 - Low Conductivity & High Strength = 15 - Low Conductivity & Low Strength = 11 - High Conductivity & Low Strength = 0.
04

Calculate the probability of low conductivity or low strength (Part b)

The probability that a strand has low conductivity or low strength involves strings that meet either or both conditions:- Total strands with low conductivity = 26 (Low Conductivity / High Strength = 15, Low Conductivity / Low Strength = 11)- High Conductivity & Low Strength: Since this is 0, its effect is non-existent.The probability of a strand having low conductivity or low strength is calculated by totaling the number of low conductivity strands and subtracting any double-counted combinations (none in this case), divided by the total strands.Probability = \( \frac{15 + 11 }{100} = \frac{26}{100} = 0.26 \).
05

Determine if the events are mutually exclusive (Part c)

Two events, 'low conductivity' and 'low strength', are mutually exclusive if they cannot occur simultaneously. From the table, there's a category for strands with both low conductivity and low strength (11 strands). Therefore, these events are not mutually exclusive, as they can occur together in certain strands.

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Key Concepts

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

Mutually Exclusive Events
When evaluating probability, understanding mutually exclusive events is essential. These are events that cannot happen at the same time. For example, when tossing a coin, the outcomes "heads" and "tails" are mutually exclusive because you can't land both on a single flip.

In the context of the wire strands exercise, we explored whether having low conductivity and low strength in a wire is mutually exclusive. Essentially, if two events cannot coexist, they are mutually exclusive.

From the given problem, we determined the wire strands can indeed have simultaneously both low conductivity and low strength, as 11 strands fit this criteria. Hence, these two events are not mutually exclusive in this scenario.

Mutually exclusive events are crucial to identify in probability, as it changes the way probabilities are calculated. If two events are mutually exclusive, the probability of both occurring at the same time is zero. Whereas, non-mutually exclusive events can be added using the general rule: \( P(A \, \text{or} \, B) = P(A) + P(B) - P(A \, \text{and} \, B) \).
Conductivity in Materials
Conductivity is a material's ability to allow the flow of electric current. In our exercise, copper wires are assessed for this crucial property.

The strands were analyzed to understand how many had high or low conductivity. Materials with high conductivity, like copper, are essential in electrical components because they transmit electricity effectively with minimal energy loss.

Materials are categorized as either conductors, semi-conductors, or insulators based on their conductivity levels.
  • Conductors allow electric charge to flow easily due to their free electrons.
  • Semi-conductors have a conductivity level between conductors and insulators and their ability to conduct electricity can change under different conditions.
  • Insulators restrain electric flow due to limited electron movement.
In the exercise, pinpointing the number of strands with high or low conductivity helps in determining the efficiency of these wires for electrical applications. Probabilities were calculated for different conductivity scenarios to infer the wire quality expected from the manufacturer.
Statistical Analysis of Data
Statistical analysis is the process of collecting and analyzing data to identify patterns and trends. This helps make informed decisions. In the given exercise, statistical analysis was essential for evaluating the quality of copper wire strands.

The first step in statistical analysis is data collection. For our exercise, this included categorizing strands by strength and conductivity levels. With 100 strands analyzed, it was possible to calculate key probabilities that helped assess the overall quality, such as the likelihood of a strand being both high in conductivity and strength.

Using properly collected data, probabilities can be accurately calculated:
  • Probability of high conductivity and high strength was calculated as \( 0.74 \).
  • Probability of low conductivity or low strength came out to be \( 0.26 \).
These calculations aid in quality control, ensuring that products meet specified standards.

In a broader scope, statistical analysis provides the backbone for making decisions based on data, informing businesses about product quality, manufacturing processes, and customer satisfaction. It transforms raw data into valuable insights, critical for any scientific or business endeavor.

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