Hello!
First of all, we will want to find the median first. We have 11 values here, so we will want to find the 6th number in our data set to find the median. This median will cut our data in half.
15,16,17,18,19,20,21,22,23,24,25
To find the IQR, we need to find the median of each side of our data set now. We exclude the 20, and look for the median on each side. This would be the third number. This gives us our 1st and 3rd quartiles.
15,16,17,18,19,20,21,22,23,24,25
Now, to find the IQR, we subtract the first and third quartiles.
23-17=6
Therefore, our IQR is [tex] \boxed {6} [/tex].
I hope this helps!
