Math Problem Statement

The five-number summary of a dataset was found to be: 46, 56, 61, 67, 70. An observation is considered an outlier if it is below or above certain values.

Solution

The image shows a statistics problem involving the five-number summary of a dataset. Let’s walk through the steps needed to determine the outlier bounds.

Five-number summary:

  • Minimum (Q0): 46
  • First Quartile (Q1): 56
  • Median (Q2): 61
  • Third Quartile (Q3): 67
  • Maximum (Q4): 70

Step 1: Interquartile Range (IQR)

The IQR measures the spread of the middle 50% of the dataThe image shows a statistics problem involving the five-number summary of a dataset. Let’s walk through the steps needed to determine the outlier bounds.

Five-number summary:

  • Minimum (Q0): 46
  • First Quartile (Q1): 56
  • Median (Q2): 61
  • Third Quartile (Q3): 67
  • Maximum (Q4): 70

Step 1: Interquartile Range (IQR)

The IQR measures the spread of the middle 50% of the
IQR=Q3Q1=6756=11\text{IQR} = Q3 - Q1 = 67 - 56 = 11

Step 2: Outlier Boundaries

  • Lower Bound:
    Lower Bound=Q11.5×IQR=561.5×11=5616.5=39.5\text{Lower Bound} = Q1 - 1.5 \times \text{IQR} = 56 - 1.5 \times 11 = 56 - 16.5 = 39.5 Any value below 39.5 will be considered a lower outlier.

  • Upper Bound:
    Upper Bound=Q3+1.5×IQR=67+1.5×11=67+16.5=83.5\text{Upper Bound} = Q3 + 1.5 \times \text{IQR} = 67 + 1.5 \times 11 = 67 + 16.5 = 83.5 Any value above 83.5 will be considered an upper outlier.

Answers:

  • An observation is considered an outlier if it is below: 39.5
  • An observation is considered an outlier if it is above: 83.5

Would you like further clarification or more examples?


5 Related Questions:

  1. What is the purpose of the IQR in detecting outliers?
  2. How is the five-number summary used to describe the spread of data?
  3. What happens if a dataset contains no outliers?
  4. How do we adjust if extreme outliers are detected beyond 3 IQRs?
  5. Can box plots visually represent outliers?

Tip: For large datasets, plotting the data using a box plot can provide a quick visualization of outliers and the five-number summary.

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Math Problem Analysis

Mathematical Concepts

Descriptive Statistics
Five-Number Summary
Outliers

Formulas

Interquartile Range (IQR) = Q3 - Q1
Lower Bound = Q1 - 1.5 * IQR
Upper Bound = Q3 + 1.5 * IQR

Theorems

Outlier detection using the IQR rule

Suitable Grade Level

Grades 9-12