Math Problem Statement

The U.S. Census Bureau frequently conducts nationwide surveys on the characteristics of U.S. households. Suppose the following data are on the number of people per household for a sample of 20 households. Find the five-number summary for this data set by hand. Report the five-number summary in the following order: Min, Q1, Median (Q2), Q3, Max

Number of

People

Frequency

1

4

2

7

3

4

4

2

5

1

6

1

7

1

Solution

To find the five-number summary (Min, Q1, Median, Q3, Max) for this dataset, we'll go through the following steps:

  1. Organize the data by listing each number of people with its corresponding frequency.
  2. Find the five-number summary, including the minimum, the quartiles (Q1, Median, Q3), and the maximum.

Step 1: Organizing the Data

The frequency table gives us the number of households corresponding to each number of people. We'll list the numbers accordingly:

  • 1 person: 4 households → 1,1,1,11, 1, 1, 1
  • 2 people: 7 households → 2,2,2,2,2,2,22, 2, 2, 2, 2, 2, 2
  • 3 people: 4 households → 3,3,3,33, 3, 3, 3
  • 4 people: 2 households → 4,44, 4
  • 5 people: 1 household → 55
  • 6 people: 1 household → 66
  • 7 people: 1 household → 77

Now, combining them into one ordered list: 1,1,1,1,2,2,2,2,2,2,2,3,3,3,3,4,4,5,6,71, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 5, 6, 7

Step 2: Finding the Five-Number Summary

  • Minimum (Min): The smallest number in the dataset is 1\mathbf{1}.

  • Maximum (Max): The largest number in the dataset is 7\mathbf{7}.

  • Median (Q2): Since we have 20 data points, the median is the average of the 10th and 11th values in the ordered list: Q2=2+22=2Q2 = \frac{2 + 2}{2} = 2

  • First Quartile (Q1): The first quartile is the median of the lower half of the data (the first 10 values). The 5th and 6th values are both 2, so: Q1=2+22=2Q1 = \frac{2 + 2}{2} = 2

  • Third Quartile (Q3): The third quartile is the median of the upper half of the data (the last 10 values). The 15th and 16th values are 3 and 4, so: Q3=3+42=3.5Q3 = \frac{3 + 4}{2} = 3.5

Final Five-Number Summary

  • Min: 1
  • Q1: 2
  • Median (Q2): 2
  • Q3: 3.5
  • Max: 7

Would you like more details or have any questions?

Here are 5 related questions for practice:

  1. How do you calculate the interquartile range (IQR) using the five-number summary?
  2. If the dataset had an extra household with 8 people, how would the five-number summary change?
  3. How would you interpret the third quartile (Q3) in this context?
  4. What does the five-number summary tell us about the spread of household sizes in this sample?
  5. How could you use this five-number summary to identify potential outliers?

Tip: Quartiles divide your data into four equal parts. Q1 is the 25th percentile, the median (Q2) is the 50th percentile, and Q3 is the 75th percentile.

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Math Problem Analysis

Mathematical Concepts

Statistics
Descriptive Statistics
Five-number Summary

Formulas

Median: (n/2)th value if odd, or the average of the (n/2)th and (n/2 + 1)th values if even
Quartiles: Q1 = median of lower half of data, Q3 = median of upper half of data

Theorems

Quartile Theorem
Median Theorem

Suitable Grade Level

Grades 6-8