Q&A for How to Find the IQR

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How do I find the IQR when the upper and lower quartile are the same number?

Community Answer

Find the IQR by subtracting Q1 from Q3. If they are the same number, the IQR equals zero.

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Question

Can the IQR be negative?

Community Answer

No, if it is done correctly, all numbers should be in ascending order, therefore the first quartile would be smaller or the same as the third quartile.

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Question

How do I find IQR of 1,3,4,5,8,9,10,11,12,14,16?

Community Answer

In 1,3,4,5,8,9,10,11,12,14,16 the median for the lower quartile is 4 and the median for the upper quartile is 12. Subtract Q3 by Q1 and that would make it 12-4 and 12-4= 8.

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If I have two middle numbers, can I add them together then subtract?

Community Answer

No, if the median (middle numbers) are 2 and 3 for example, then the median would be 2.5.

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Is the inter quartile range the same as the median?

Community Answer

No. You have to find the median first, then find the median again of the two sides of the original median, and subtract.

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What should I do if there are four numbers in one area?

Community Answer

Find the median of the four numbers. For example, with 4, 6, 8, 10 then it's 7.

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Question

Can the IQR be a negative numbler?

Community Answer

No. If you do it right, you should have a number equal to or greater than zero.

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When using the formula, do I add the two numbers in the quartile together and then subtract them?

Community Answer

The quartiles of any distribution are the values with cumulative proportions 0.25 and 0.75. The interquartile range IQR is the distance between the first and third quartiles of a distribution. (a) What is the value of the IQR for the standard Normal distribution? (Round your answer to four decimal places.) (b) There is a constant c such that IQR = cσ for any Normal distribution N(μ, σ). What is the value of c? (Round your answer to four decimal places.)

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Question

Do I add the two numbers in quartile 3 and 1 together?

Community Answer

No, you don't add them. You must subtract the two quartiles; the answer will be the IQR.

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What do I do when Quartile 3 is larger than Quartile 1?

Community Answer

It shouldn't be larger than quartile 1. Make sure you have arranged your data set in ascending order before finding your quartiles.

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How do I determine the carnality of the subset of any given set?

Community Answer

Use the formula 2 to the power n, when = the number of terms. For example: 2,3,4,7,9. The are 5 numbers. 2 to the power 5 = 32. 32 is the max number subset which could be made out of 5 terms.

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How do I use the IQR to find outliers?

Community Answer

The IQR is not made to find outliers. To find outliers, just look at the data set.

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Question

How do I separate sets of data in quarters when finding the IQR?

Community Answer

First, you order the data in ascending order, then you split it. If it is even, the line will be in between the two middle numbers, but if it is odd the middle number will be the line. Now you have the first quartile and third quartile.

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What is the reason for finding the IQR?

Community Answer

The IQR tells us how the range of variability should look within a data set. This means that if the average score on a test is 80%, and the IQR is 14%, you should expect the highest score in the class to be 94% and the lowest score to be 66%. IQRs are often used in science to make sure that all experiment results are accurate, as mistakes can happen that will produce wonky results. By using IQR, scientists can determine which data sets look like they were produced by mistake.

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How do I find the IQR for the numbers 1, 2, 3, 4, 5, 6, 7, 8?

StrangelyQuiet

Top Answerer

To find the IQR: Q1 is at the 2.25th point, which is 2.25; Q3 is at the 6.75th point, which is 6.75. So, IQR = 6.75 - 2.25 = 4.5.

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What are the median, upper quartile, lower quartile, and interquartile range of 8, 9, 10, 14, 15, 17, 18, 18?

StrangelyQuiet

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The median is 12, the lower quartile is 8, the upper quartile is 17, and the interquartile range is 8.5.

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How do I find the IQR of the data set: 25, 31, 27, 33, 41, 39, 48, 46, 52?

StrangelyQuiet

Top Answerer

First, arrange the values in order: 25, 27, 31, 33, 39, 41, 46, 48, 52. Determine Q1 as the 2.5th point, which is 29, and Q3 as the 7.5th point, which is 47. The IQR is 47 - 29 = 18.

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What is the IQR of the data set: 78, 79, 80, 81, 82, 83, 84?

StrangelyQuiet

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Q1 is the 2nd point, which is 79, and Q3 is the 6th point, which is 83. Thus, the IQR is 83 - 79 = 4.

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What should I do if there are 5 numbers in one set? For example: 8, 9, 10, 11, 12. I know 10 is the median, but what are Q1 and Q2?

StrangelyQuiet

Top Answerer

Q2 is the median, which you already found to be 10. Q1 is calculated as the 1.5th point, which equals 8.5.

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How do I find the IQR if one of the numbers has a decimal, such as 42.5?

StrangelyQuiet

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You can still find the IQR with decimal values; just make sure to arrange them in order and locate Q1 and Q3 correctly.

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What should I do if there are 9 numbers?

StrangelyQuiet

Top Answerer

The formula for the IQR still applies. If a quartile value falls between two numbers, use the midpoint between them. For example, if Q1 falls at the 3.5th position, calculate the midpoint between the numbers at positions 3 and 4.

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What is the IQR of these numbers: 2.4, 5.4, 6.5, 8.0, 8.7, 12.4, 14.6, 20.4, 21.5?

StrangelyQuiet

Top Answerer

Q1 = (9+1)/4th position = 2.5th position = (5.4+6.5)/2 = 5.95; Q3 = 3(9+1)/4th position = 7.5th position = (14.6+20.4)/2 = 17.5; IQR = 17.5 - 5.95 = 11.55.

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How do I find the interquartile range of 8, 11, 13, 15, 18, 26, 29, 31, 33, 36?

StrangelyQuiet

Top Answerer

To find the interquartile range (IQR), calculate Q1 as the 2.75th value (12.5) and Q3 as the 8.25th value (31.5). Subtract Q1 from Q3: IQR = 31.5 - 12.5 = 19.

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How do I find the interquartile range of the numbers 1, 10, 25, 50, 75, 90, and 99?

StrangelyQuiet

Top Answerer

To find the interquartile range (IQR), first determine Q1 as the value at the (7+1)/4, which is the 2nd point or 10. Next, determine Q3 as the value at 3(7+1)/4, which is the 6th point or 90. Finally, subtract Q1 from Q3: IQR = 90 - 10 = 80.

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What should I do if I have some numbers that repeat themselves in my dataset?

StrangelyQuiet

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Keep the repeating numbers in the dataset and place them next to each other. When finding Q1 or Q3, if it lands between two identical numbers, simply choose that number.

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How do I find the interquartile range if the numbers are not in order, like 4, 9, 2, 11, 7, 3?

StrangelyQuiet

Top Answerer

Arrange the numbers in ascending order: 2, 3, 4, 7, 9, 11. Then calculate: Q1 = 2.75, Q3 = 9.5, so IQR = 9.5 - 2.75 = 6.75.

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How do I find the IQR of the following set of marks: 2, 2, 3, 1, 6, 4, 3, 4, 3, 5?

StrangelyQuiet

Top Answerer

First, order the values: 1, 2, 2, 3, 3, 3, 4, 4, 5, 6. Then, Q1 (first quartile) is at the 2.75th point, which is 2, and Q3 (third quartile) is at the 8.25th point, which is 4.25. The IQR (interquartile range) is 4.25 - 2 = 2.25.

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What is the IQR for the data set 38, 38, 86, 90, 100, 107, 110, 240?

I_l1ke_gam3s

Community Answer

First be sure the numbers are arranged in ascending or descending order. Then to find the IQR, determine the median of the data set, which is the middle number if there is an odd number of numbers, or the average of the two middle numbers if there is an even number of numbers. Now find Q1 by determining the median of all numbers less than the set's median. For Q3, determine the median of the numbers greater than the set's median. The IQR is the difference between Q3 and Q1. In other words, Q3 - Q1.

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What is the IQR of the data set (4,5,5,5,5,7,7,8,9)?

I_l1ke_gam3s

Community Answer

The median of the data set is 5. The Q1 median is also 5. The Q3 median is (7 + 8)/2 = 15/2 = 7.5. The IQR is 7.5 - 5 = 2.5.

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What is the IQR of 0,5,10,15,20,25,30,35,40,45,50,55 and 60?

I_l1ke_gam3s

Community Answer

Find the median of the data set, then find Q1, then find Q3. The IQR is Q3 - Q1. Q1 is the median of all the numbers to the left of the median. Q3 is the median of all the numbers to the right of the median.

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