Math Problem Statement

suppose a normally distributed set of data with 5500 observations has a mean of 197 and a standard deviation of 17 use the 68-95-99.7 rule to determine the number of observations in the data set expected to above a value of 163 round your answer to the nearest whole value

Solution

The 68-95-99.7 rule, also known as the empirical rule, tells us how data in a normal distribution is distributed within standard deviations of the mean. Here's a breakdown of how to apply this rule:

  1. Given Data:

    • Mean (μ\mu) = 197
    • Standard deviation (σ\sigma) = 17
    • Total observations = 5500
    • We are asked to find the number of observations expected to be above 163.
  2. Calculate the z-score for the value 163:

    z=xμσ=16319717=3417=2z = \frac{x - \mu}{\sigma} = \frac{163 - 197}{17} = \frac{-34}{17} = -2

    So, the value 163 is 2 standard deviations below the mean.

  3. Using the empirical rule:

    • Approximately 95% of the data falls within 2 standard deviations of the mean (from μ2σ\mu - 2\sigma to μ+2σ\mu + 2\sigma).
    • Therefore, the remaining 5% of the data is outside this range.
      • Since the normal distribution is symmetric, 2.5% of the data lies below 2 standard deviations below the mean.
      • 2.5% of the data lies above 2 standard deviations above the mean.
  4. Finding the percentage of data above 163:

    • If 2.5% of the data is below 163, then the remaining 97.5% of the data lies above 163.
  5. Number of observations above 163: 0.975×5500=5362.50.975 \times 5500 = 5362.5

    Rounding to the nearest whole number, the expected number of observations above 163 is 5363.

Would you like a further breakdown of any steps?

Related Questions:

  1. What is the z-score of a value greater than 197?
  2. How would the empirical rule apply if the standard deviation was 20 instead of 17?
  3. What percentage of data would lie above 2 standard deviations?
  4. How many observations would be expected below a value of 163?
  5. How can the 68-95-99.7 rule be used to find values above or below 1 standard deviation from the mean?

Tip: Z-scores help to standardize values from different normal distributions to easily compare them.

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Math Problem Analysis

Mathematical Concepts

Statistics
Normal Distribution
Z-Score
Empirical Rule (68-95-99.7 Rule)

Formulas

Z-Score Formula: z = (x - μ) / σ
Empirical Rule: 68% of data within 1σ, 95% within 2σ, 99.7% within 3σ

Theorems

Empirical Rule
Normal Distribution Properties

Suitable Grade Level

Grades 10-12