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Consider a sample with a mean of 500 and a standard deviation of \(100 .\) What are the \(z\) -scores for the following data values: \(520,650,500,450,\) and \(280 ?\)

Short Answer

Expert verified
The z-scores are 0.2, 1.5, 0, -0.5, and -2.2 for data values 520, 650, 500, 450, and 280 respectively.

Step by step solution

01

Understanding Z-Score Formula

The z-score is calculated using the formula: \[ z = \frac{(X - \mu)}{\sigma} \] where \( X \) is the data value, \( \mu \) is the mean, and \( \sigma \) is the standard deviation.
02

Calculate Z-Score for X = 520

For \( X = 520 \): \[ z = \frac{(520 - 500)}{100} = \frac{20}{100} = 0.2 \] The z-score for 520 is 0.2.
03

Calculate Z-Score for X = 650

For \( X = 650 \): \[ z = \frac{(650 - 500)}{100} = \frac{150}{100} = 1.5 \] The z-score for 650 is 1.5.
04

Calculate Z-Score for X = 500

For \( X = 500 \): \[ z = \frac{(500 - 500)}{100} = \frac{0}{100} = 0 \] The z-score for 500 is 0.
05

Calculate Z-Score for X = 450

For \( X = 450 \): \[ z = \frac{(450 - 500)}{100} = \frac{-50}{100} = -0.5 \] The z-score for 450 is -0.5.
06

Calculate Z-Score for X = 280

For \( X = 280 \): \[ z = \frac{(280 - 500)}{100} = \frac{-220}{100} = -2.2 \] The z-score for 280 is -2.2.

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Key Concepts

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

Standard Deviation
The standard deviation is a statistical measure that describes the amount of variation or dispersion in a set of data values. To put it simply, it tells us how much the data points deviate from the mean, or average, of the dataset. A small standard deviation indicates that the values are closely clustered around the mean, whereas a large standard deviation implies that the values are more spread out. In our exercise, we have a standard deviation of 100. This means that the majority of data points lie within 100 units of the mean (500, in this case). Understanding standard deviation is crucial when analyzing data because it helps you to grasp how diverse your data set is. It is a key component in calculating the z-score, which allows us to determine how individual data points relate to the overall distribution.
Mean Calculation
The mean of a dataset is also known as the average. It is calculated by adding all the numbers together and then dividing by the number of values. The mean provides a central value that represents the informative summary of a dataset. For the given exercise, the mean is already provided as 500. This simplifies our task as we do not need to calculate it ourselves. However, understanding how the mean is calculated is essential for proper data analysis, as it is often used in conjunction with other statistical tools. Calculating the mean helps in understanding the general trend of data. It is the foundation for further computations, such as the standard deviation and z-scores, to interpret data more deeply.
Data Analysis
Data analysis involves interpreting numerical data to extract meaningful insights and draw conclusions. In the context of our exercise, calculating the z-score for each data value helps to analyze how far or close each value is from the mean of the dataset. Z-scores allow us to understand the position of a data point in terms of the overall distribution. A z-score can tell you whether a data point is typical for a given dataset or falls outside of the norm. For example: - A positive z-score indicates the data point is above the mean. - A negative z-score shows it is below the mean. - A z-score near to 0 implies it is very close to the mean. By calculating these scores in our dataset with a mean of 500 and a standard deviation of 100, we can easily discern how data points like 520, 650, 500, 450, and 280 differ from average conditions. This kind of analysis is beneficial in fields ranging from educational research to consumer data analytics, allowing experts to make informed decisions based on statistical evidence.

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