Math Problem Statement

Use the following data to answer questions 11 - 26

Score z-score Percentile 52 50 43 38 38 37 35 35 35 28 27 27 25 23

The interquartile range for the Score column is _______________.

Group of answer choices

13

14

11

12

Solution

To calculate the interquartile range (IQR) for the Score column, we first need to find the first quartile (Q1) and the third quartile (Q3) and then compute the difference between them:

IQR=Q3Q1\text{IQR} = Q3 - Q1

Step 1: Organize the data in ascending order.

Scores (sorted): 23, 25, 27, 27, 28, 35, 35, 35, 37, 38, 38, 43, 50, 52

There are 14 data points in total.

Step 2: Find Q1 and Q3.

  • Q1 (25th percentile) is the value that marks the first quartile, which is the median of the lower half of the data (excluding the overall median).
  • Q3 (75th percentile) is the value that marks the third quartile, which is the median of the upper half of the data.

Lower half (first 7 scores):

23, 25, 27, 27, 28, 35, 35

  • The median of this lower half (Q1) is 27.

Upper half (last 7 scores):

35, 37, 38, 38, 43, 50, 52

  • The median of this upper half (Q3) is 38.

Step 3: Calculate the IQR.

IQR=Q3Q1=3827=11\text{IQR} = Q3 - Q1 = 38 - 27 = 11

The interquartile range is 11.

So, the correct answer is:

  • 11

Would you like more details or have any further questions?

5 Related Questions:

  1. How is the interquartile range different from the standard deviation?
  2. What is the median score of the data provided?
  3. How do quartiles divide a dataset, and what is their significance?
  4. What happens to the IQR if outliers are present in the data?
  5. How can the IQR be used to detect outliers in a dataset?

Tip:

The interquartile range (IQR) is a robust measure of variability and is less sensitive to outliers than standard deviation.

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Math Problem Analysis

Mathematical Concepts

Statistics
Interquartile Range
Quartiles
Data Sorting

Formulas

IQR = Q3 - Q1

Theorems

Quartile Theorem
Percentile Division

Suitable Grade Level

Grades 10-12