Math Problem Statement

Suppose that a distribution of 500 items has mean 110 and standard deviation 8. Find the z-score of the item x = 130.

Solution

To find the z-score of the item x=130x = 130 given the mean μ=110\mu = 110 and standard deviation σ=8\sigma = 8, we use the z-score formula:

z=xμσz = \frac{x - \mu}{\sigma}

Substituting the values:

z=1301108z = \frac{130 - 110}{8}

z=208=2.5z = \frac{20}{8} = 2.5

Final Answer:

The z-score is 2.5.


Would you like me to explain how to interpret this z-score or go into more details?

Here are 5 related questions to deepen your understanding:

  1. What does a positive z-score indicate in a distribution?
  2. How would the z-score change if the standard deviation were smaller?
  3. What is the z-score for an item x=102x = 102 with the same mean and standard deviation?
  4. How do z-scores help compare values from different distributions?
  5. What percentage of the data falls below a z-score of 2.52.5 in a normal distribution?

Tip: A z-score tells you how many standard deviations a value is away from the mean. Positive z-scores are above the mean, and negative z-scores are below the mean.

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Math Problem Analysis

Mathematical Concepts

Statistics
Standard Deviation
Z-Score Calculation

Formulas

z = (x - μ) / σ

Theorems

Properties of Z-Scores

Suitable Grade Level

Grades 9-12