Posted by B.B. on Wednesday, July 29, 2009 at 1:53pm.
Can someone show me how to calculate the inner quartile range for the data set given? { 72, 80, 80, 82, 88, 90, 96}. Thanks.

Math  MathMate, Wednesday, July 29, 2009 at 2:04pm
1. arrange the numbers in ascending numerical order:
{ 72, 80, 80, 82, 88, 90, 96}.
2. Find the median, which is the middle number of the list. In the given case, the middle number of 7 number is the fourth, namely 82.
{ 72, 80, 80, 82, 88, 90, 96}
3. Find the first quartile:
Disregard the median and numbers higher than the median. For the remaining numbers, repeat step number 2, this is the first quartile. (80)
{ 72, 80, 80 ...}.
4. Find the third quartile: repeat step 3 using the upper half of the list of numbers.
{ ... 88, 90, 96}.
5. We should end up with the data set as follows:
{ 72, 80, 80, 82, 88, 90, 96}.
The inner quartile range is the difference between the third and the fisrt quartiles, namely 9080=10 in the given case.
Note that there are specific procedures for finding the median when there the number of numbers is even. 
Math  B.B., Wednesday, July 29, 2009 at 2:51pm
Thank you.