Understanding Quartiles and IQR

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| By Thames
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Thames
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Quizzes Created: 7116 | Total Attempts: 9,522,086
| Questions: 20 | Updated: Oct 31, 2025
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1) Which is the best interpretation of an IQR of 6 cm for this data?

Explanation

The IQR measures the spread of the middle 50% of the data, so the best interpretation is that the middle half of plant heights are spread across 6 cm.

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About This Quiz
Understanding Quartiles And Iqr - Quiz

Time to dive into the world of quartiles and IQR! This quiz will help you unlock the power of the interquartile range (IQR), a measure of spread that tells you how data is distributed in the middle 50%. By the end, you'll understand how the IQR helps you identify how... see morespread out the middle data is, and why it’s so useful in analyzing real-world data. Ready to master the range that matters most? Let's get started! see less

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2) What is the median number of pages read?

Explanation

To find the median, arrange the data in order: 12, 18, 25, 30, 30, 33, 37, 40, 42, 45, 47, 50. There are 12 data points, so the median is the average of the 6th and 7th values: (33 + 37) / 2 = 35.

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3) What is Q1 for this data set?

Explanation

Q1 is the median of the lower half of the data. The lower half is: 12, 18, 25, 30, 30, 33. The median of this set is 27.5.

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4) What is Q3 for this data set?

Explanation

Q3 is the median of the upper half of the data. The upper half is: 37, 40, 42, 45, 47, 50. The median of this set is 43.5.

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5) What is the IQR for this data set?

Explanation

The IQR is the difference between Q3 and Q1: 43.5 - 27.5 = 16.

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6) Which statement best describes what the IQR represents for this class?

Explanation

The IQR measures the spread of the middle 50% of the data.

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7) What is the IQR of the data represented by the box plot?

Explanation

The IQR is the distance between Q1 and Q3. From the box plot, calculate Q1 and Q3, then find the difference.

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8) Which interval contains the middle 50 percent of the data?

Explanation

The middle 50% of the data is represented by the IQR, which is between Q1 and Q3. From the box plot, find Q1 and Q3 to identify the correct interval.

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9) If a new data point of 60 is added, which measure is most affected?

Explanation

Adding a high data point like 60 will affect the maximum and possibly the IQR but not Q1 or the median significantly.

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10) What is the median score?

Explanation

The data set is: 55, 68, 72, 74, 75, 78, 81, 83, 85, 89, 92. The median is the middle value, which is 78.

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11) What are Q1 and Q3?

Explanation

To find Q1 and Q3, divide the data into two halves: Q1 is the median of the lower half: 68. Q3 is the median of the upper half: 85.

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12) What is the IQR?

Explanation

The IQR is the difference between Q3 and Q1: 85 - 72 = 13.

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13) Which statement is true about the IQR?

Explanation

The IQR measures the spread of the middle 50% of the data, not the entire data set.

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14) What is Q1?

Explanation

The lower half of the data set is: 5, 7, 12, 12, 14, 15. The median of this set is 12.

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15) What is Q3?

Explanation

The upper half of the data set is: 18, 18, 21, 21, 24, 30. The median of this set is 21.

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16) What is the IQR?

Explanation

The IQR is the difference between Q3 and Q1: 21 - 12 = 9.

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17) Which class has the larger IQR?

Explanation

Class A’s IQR is (30 - 18 = 12), and Class B’s IQR is (36 - 12 = 24). Class B has the larger IQR.

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18) What does the larger IQR tell you about that class?

Explanation

A larger IQR means that the middle 50% of the data points are more spread out.

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19) If both classes add the same high outlier, which statement is true?

Explanation

The IQR is not significantly affected by the addition of an outlier unless it changes Q1 or Q3. Since the outlier is high, it’s more likely to affect the range than the IQR.

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20) What is Q3 for the plant heights?

Explanation

The upper half of the data set is: 16, 18, 20, 25. The median of this set is 20.

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  • Answered
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Which is the best interpretation of an IQR of 6 cm for this data?
What is the median number of pages read?
What is Q1 for this data set?
What is Q3 for this data set?
What is the IQR for this data set?
Which statement best describes what the IQR represents for this class?
What is the IQR of the data represented by the box plot?
Which interval contains the middle 50 percent of the data?
If a new data point of 60 is added, which measure is most affected?
What is the median score?
What are Q1 and Q3?
What is the IQR?
Which statement is true about the IQR?
What is Q1?
What is Q3?
What is the IQR?
Which class has the larger IQR?
What does the larger IQR tell you about that class?
If both classes add the same high outlier, which statement is true?
What is Q3 for the plant heights?
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