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Use the following data. An automobile company tested a new electric engine, and found the following results. In twenty tests of the range (in mi) that a certain model car could travel (under specified conditions ) before the batteries needed recharging. $$\begin{aligned}&143,148,146,144,149,144,150,148,148,144\\\ &153,146,147,146,147,149,145,151,149,148\end{aligned}$$ Find the relative frequencies.

Short Answer

Expert verified
Relative frequencies are 143: 0.05, 144: 0.15, 145: 0.05, 146: 0.15, 147: 0.10, 148: 0.20, 149: 0.15, 150: 0.05, 151: 0.05, 153: 0.05.

Step by step solution

01

Organize Data

First, we need to organize the data to find the frequency of each result. Let's list all the data values: 143, 148, 146, 144, 149, 144, 150, 148, 148, 144, 153, 146, 147, 146, 147, 149, 145, 151, 149, 148.
02

Count Frequencies

Next, we count how many times each unique value appears in the data set. The counts are as follows: - 143: 1 - 144: 3 - 145: 1 - 146: 3 - 147: 2 - 148: 4 - 149: 3 - 150: 1 - 151: 1 - 153: 1
03

Calculate Relative Frequencies

Relative frequency is calculated by dividing the frequency of each value by the total number of observations (20 in this case). - Relative frequency of 143: \( \frac{1}{20} = 0.05 \)- Relative frequency of 144: \( \frac{3}{20} = 0.15 \)- Relative frequency of 145: \( \frac{1}{20} = 0.05 \)- Relative frequency of 146: \( \frac{3}{20} = 0.15 \)- Relative frequency of 147: \( \frac{2}{20} = 0.10 \)- Relative frequency of 148: \( \frac{4}{20} = 0.20 \)- Relative frequency of 149: \( \frac{3}{20} = 0.15 \)- Relative frequency of 150: \( \frac{1}{20} = 0.05 \)- Relative frequency of 151: \( \frac{1}{20} = 0.05 \)- Relative frequency of 153: \( \frac{1}{20} = 0.05 \)
04

Summarize Relative Frequencies

The relative frequencies for the results are as follows: - 143: 0.05 - 144: 0.15 - 145: 0.05 - 146: 0.15 - 147: 0.10 - 148: 0.20 - 149: 0.15 - 150: 0.05 - 151: 0.05 - 153: 0.05

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Key Concepts

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

Relative Frequencies
Relative frequencies help us understand how often each data point appears compared to the total number of observations. In this way, we can grasp the data distribution without needing to know the absolute counts.When we calculate the relative frequency, we take the count of a specific data point and divide it by the total number of data points. This results in a proportion or a percentage, which gives us a normalized understanding of our data.The formula is simple and consistent:\[ \text{Relative Frequency} = \frac{\text{Frequency of a value}}{\text{Total number of observations}} \]For example, if you have a value that appears 4 times in a dataset of 20 items, the relative frequency would be calculated as:\[ \frac{4}{20} = 0.20 \text{ or 20\%} \]This gives a clear view of each data point's significance in the whole dataset.
Data Organization
Before any meaningful analysis can be made, data must be organized in a way that reveals patterns and relationships. Organizing data involves listing and sometimes grouping them into a more consumable format. For this exercise, we started by listing all readings or results of the car's range tests. Then, we counted how many times each occurred. This step might seem straightforward, but it's vital as it transforms raw data into a readily understandable form. Think of data organization as setting the stage. Once your data is organized, it's easier to spot trends, errors, or even outliers. Here's a simple process:
  • List each unique data value.
  • Count the frequency of each value.
  • Sort the values for better interpretation.
Taking the time to organize can save a lot of effort in later analysis, making it a crucial first step.
Frequency Distribution
Frequency distribution is a table or an organized list that shows the frequency (or count) of various outcomes in a sample or population. It simply outlines how often each value occurs, offering a summary of the data set. Creating a frequency distribution is one of the easiest ways to reveal data patterns and trends:
  • Identify each distinct data point in your dataset.
  • Record the number of times each data point appears (its frequency).
For this exercise, when we tabulated the frequency of car range results, we easily visualized how common or rare each range value was. A well-structured frequency distribution helps to illuminate data that might otherwise remain hidden and serves as a stepping stone to deeper statistical analysis.
Mathematical Analysis
Mathematical analysis in statistics often follows the preliminary steps of organizing data and frequency analysis. It offers a deeper dive into the data, providing insights that simple counting cannot. In our discussion, we can break this analysis down into a few critical tasks:
  • Calculating totals and averages: such as the mean of the data set, which offers a central tendency.
  • Understanding variability: calculating the range or standard deviation to comprehend the spread of data points.
  • Interpreting results: considering what relative frequencies say about probability and real-world implications.
These mathematical tools allow us to go beyond surface observations to uncover correlations, causations, and predictions. As you become comfortable with these analyses, interpreting statistical results becomes much clearer and more efficient.

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Most popular questions from this chapter

Use the following sets of numbers. A: 3,6,4,2,5,4,7,6,3,4,6,4,5,7,3 B: 25,26,23,24,25,28,26,27,23,28,25 C: 0.48,0.53,0.49,0.45,0.55,0.49,0.47,0.55,0.48,0.57, 0.51,0.46,0.53,0.50,0.49,0.53 D: 105,108,103,108,106,104,109,104,110,108,108, 104,113,106,107,106,107,109,105,111,109,108 Determine the mode of the numbers of the given set. Set \(C\)

Find the indicated quantities. The members of a high school class were asked to estimate the number of text messages they sent each day, with the following results. $$\begin{array}{l|c|c|c|c|c}\text {Messages} & 0-25 & 26-50 & 51-75 & 76-100 & 101-125 \\\\\hline \text {Students} & 2 & 7 & 18 & 41 & 56 \\\\\text {Messages} & 126-150 & 151-175 & 176-200 & 201-225 \\\\\hline \text {Students} & 32 & 8 & 3 & 3\end{array}$$ Draw a histogram for these data.

Use the following data. An automobile company tested a new electric engine, and found the following results. In twenty tests of the range (in mi) that a certain model car could travel (under specified conditions ) before the batteries needed recharging. $$\begin{aligned}&143,148,146,144,149,144,150,148,148,144\\\ &153,146,147,146,147,149,145,151,149,148\end{aligned}$$ Draw a histogram for the data of Exercise 7 .

Use the following sets of numbers. They are the same as those used in Exercise 22.2. $$A: 3,6,4,2,5,4,7,6,3,4,6,4,5,7,3$$ $$B: 25,26,23,24,25,28,26,27,23,28,25$$ $$C: 0.48,0.53,0.49,0.45,0.55,0.49,0.47,0.55,0.48,0.57,0.51,0.46,0.53,0.50,0.49,0.53$$ $$D: 105,108,103,108,106,104,109,104,110,108,108,104,113,106,107,106,107,109,105,111,109,108$$ use the statistical feature of a calculator to find the arithmetic mean and the standard deviation s for the indicated sets of numbers. $$\operatorname{set} A$$

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