Math Problem Statement

The 2000 U.S. Census asked every household to report information on each person living there. Suppose for a sample of 30 households selected, the number of persons living in each was reported as follows: 2, 3, 1, 2, 6, 4, 2, 1, 5, 3, 3, 2, 1, 3, 1, 2, 4, 2, 1, 2, 8, 3, 3, 2, 1, 3, 3, 2, 1, 3. Compute the mean, median, mode, range, lower and upper quartiles, and interquartile range.

Solution

Let's solve the problem step-by-step based on the data provided:

The data given:

2, 3, 1, 2, 6, 4, 2, 1, 5, 3, 3, 2, 1, 3, 1, 2, 4, 2, 1, 2, 8, 3, 3, 2, 1, 3, 3, 2, 1, 3


1. Mean

The mean (average) is calculated as:

Mean=Sum of all data pointsNumber of data points\text{Mean} = \frac{\text{Sum of all data points}}{\text{Number of data points}}

  • Sum of the data points: 2+3+1+2+6+4+2+1+5+3+3+2+1+3+1+2+4+2+1+2+8+3+3+2+1+3+3+2+1+3=742 + 3 + 1 + 2 + 6 + 4 + 2 + 1 + 5 + 3 + 3 + 2 + 1 + 3 + 1 + 2 + 4 + 2 + 1 + 2 + 8 + 3 + 3 + 2 + 1 + 3 + 3 + 2 + 1 + 3 = 74
  • Number of data points: 3030

Mean=74302.47\text{Mean} = \frac{74}{30} \approx 2.47


2. Median

The median is the middle value when the data is sorted in ascending order.

  • Sorted data:
    1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 5, 6, 8

  • Since there are 30 data points (even number), the median is the average of the 15th and 16th values in the sorted list.

15th value = 2
16th value = 2

Median=2+22=2\text{Median} = \frac{2 + 2}{2} = 2


3. Mode

The mode is the value that appears most frequently.

  • Frequency table:
    1 appears 6 times
    2 appears 10 times
    3 appears 8 times
    4 appears 2 times
    5 appears 1 time
    6 appears 1 time
    8 appears 1 time

The mode is 2 since it appears the most frequently (10 times).


4. Range

The range is the difference between the largest and smallest values.

Range=MaximumMinimum=81=7\text{Range} = \text{Maximum} - \text{Minimum} = 8 - 1 = 7


5. Lower and Upper Quartiles (Q1 and Q3)

  • Q1 (lower quartile) is the median of the first half of the sorted data (lower 15 values).
  • Q3 (upper quartile) is the median of the second half of the sorted data (upper 15 values).

Lower half (first 15 values):

1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2
Q1 = median of these values = 2

Upper half (last 15 values):

2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 5, 6, 8
Q3 = median of these values = 3


6. Interquartile Range (IQR)

The IQR is the difference between Q3 and Q1:

IQR=Q3Q1=32=1\text{IQR} = Q3 - Q1 = 3 - 2 = 1


Final Results

  1. Mean: 2.472.47
  2. Median: 22
  3. Mode: 22
  4. Range: 77
  5. Q1: 22, Q3: 33
  6. Interquartile Range (IQR): 11

Do you want me to explain any step in detail? Let me know!
Here are some related questions for practice:

  1. How is the mean affected by an outlier in the data?
  2. What is the difference between mean and median?
  3. Can a data set have more than one mode?
  4. How do you calculate the IQR for an odd number of data points?
  5. What does the range tell us about a data set?

Tip: The IQR (Interquartile Range) is a robust measure of spread because it is not affected by extreme values (outliers).

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Measures of Central Tendency
Measures of Spread
Descriptive Statistics

Formulas

Mean = (Sum of all data points) / (Number of data points)
Median = Middle value of sorted data (or average of two middle values for even data points)
Mode = Value that occurs most frequently
Range = Maximum value - Minimum value
Interquartile Range (IQR) = Q3 - Q1

Theorems

Quartile theorem
Interquartile range definition

Suitable Grade Level

Grades 8-10