Based on what you have studied in this unit, reflect and answer the following questions:What are the main characteristics of the normal distribution?Why is it advantageous to use the Z scores?For a standard normal distribution, about 68% of values falls within one standard deviation of the mean; about 95% falls within two standard deviations; and about 99.7% falls within three standard deviations. Suppose the distribution of math scores in the SAT follow a normal distribution with a mean µ=700 and a standard deviation σ=150.Calculate the Z-score for an SAT Math score of 600. Interpret it in your own word.Find the interval [a, b] that captures 68% of the SAT Math score in this example.Find the interval [a, b] that captures 95% of the SAT Math score in this example.Find the interval [a, b] that captures 99.7% of the SAT Math score in this example.
Question
Based on what you have studied in this unit, reflect and answer the following questions:What are the main characteristics of the normal distribution?Why is it advantageous to use the Z scores?For a standard normal distribution, about 68% of values falls within one standard deviation of the mean; about 95% falls within two standard deviations; and about 99.7% falls within three standard deviations. Suppose the distribution of math scores in the SAT follow a normal distribution with a mean µ=700 and a standard deviation σ=150.Calculate the Z-score for an SAT Math score of 600. Interpret it in your own word.Find the interval [a, b] that captures 68% of the SAT Math score in this example.Find the interval [a, b] that captures 95% of the SAT Math score in this example.Find the interval [a, b] that captures 99.7% of the SAT Math score in this example.
Solution
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The main characteristics of the normal distribution are:
- It is symmetric: The left half of the distribution is a mirror image of the right half.
- The mean, median, and mode are all equal and are located at the center of the distribution.
- It is unimodal: It has one peak.
- The distribution is defined by two parameters: the mean (µ) and the standard deviation (σ).
- The total area under the curve is 1.
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Z-scores are advantageous because they allow us to compare scores from different normal distributions. They tell us how many standard deviations away a score is from the mean. This standardizes the score and allows for comparison across different scales.
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To calculate the Z-score for an SAT Math score of 600, we use the formula Z = (X - µ) / σ. Here, X is the score, µ is the mean, and σ is the standard deviation. So, Z = (600 - 700) / 150 = -0.67. This means that the score of 600 is 0.67 standard deviations below the mean.
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For a standard normal distribution, 68% of values fall within one standard deviation of the mean. So, the interval that captures 68% of the SAT Math score is [µ - σ, µ + σ] = [700 - 150, 700 + 150] = [550, 850].
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Similarly, 95% of values fall within two standard deviations of the mean. So, the interval that captures 95% of the SAT Math score is [µ - 2σ, µ + 2σ] = [700 - 2150, 700 + 2150] = [400, 1000].
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Finally, 99.7% of values fall within three standard deviations of the mean. So, the interval that captures 99.7% of the SAT Math score is [µ - 3σ, µ + 3σ] = [700 - 3150, 700 + 3150] = [250, 1150].
Similar Questions
Suppose the scores on an exam are normally distributed with a mean μ = 75 points and standard deviation σ = 8 points.What is the exam score for an exam whose z-score is 1.25? 65 75 85 0.8944 0.1056
There are two college entrance exams that are often taken by students, Exam A and Exam B. The composite score on Exam A is approximately normally distributed with mean 20.7 and standard deviation 5.1. The composite score on Exam B is approximately normally distributed with mean 1036 and standard deviation 214. Suppose you scored 25 on Exam A and 1182 on Exam B.a) What is the z-score of Exam A?
.Question 15You know that for variable A μ = 1400 and σ = 300. You alsoknow that the variable is normally distributed. You decide to change the scores of this variableinto z-scores. What is the mean and standard deviation of this new distribution?1 pointCannot be calculated on the basis of this information.Mean = 1400, standard deviation = 300.Mean = 0, standard deviation = 1.Mean = 1400, standard deviation = 1.
Which of the following statements are TRUE about the normal distribution? Check all that apply.The area to the left of a z-score plus the area to the right of that same z-score will always equal 1.A data value with z-score = -1.5 is located 1.5 standard deviations below the mean.The Empirical Rule only applies when a value is exactly 1, 2, or 3 standard deviations away from the mean.The mean corresponds to the z-score of 1.A z-score is the number of standard deviations a specific data value is from the mean of the distribution.
A standardized value, commonly called a z-score relies on the values of Group of answer choicessample standard deviation and the meanmedianmodeaverage distribution
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