+0

# What did I do wrong?

0
247
4
+484

My Work:

Okay so the IQR is the range of the middle half of the data set, or the difference between the third and first quartiles.

I lined up the numbers from least to greatest:

10, 12, 14, 15, 15.5, 16, 17.5, 18, 19

Then I found the first and third quartiles.

Min       Q1        Q2          Q3        Max

10, 12, 14, 15, 15.5, 16, 17.5, 18, 19

So then I did 17.5 - 14 = 3.5 This doesn't match any of the choices above.

Feb 7, 2019

#1
+105411
+1

10    12   14    15      15.5     16   17.5    18    19

Q2  =   15.5

Q1 =     [12 + 14] / 2   =    26 / 2  =   13

Q3  =  [ 17.5 + 18 ] / 2   =  17.75

So....the IQR is just     17.75 - 13   =   4.75

Feb 7, 2019
#2
+484
+1

Can you tell me why those numbers had to be added so I know for future questions like this?

awsometrunt14  Feb 7, 2019
#3
+105411
+2

We are actually finding 3 medians

The first is the median of the data set = 15.5   =  Q2

Then....we look at the four data points to the left of Q2

These are 10 12   14  15

The median of these  = [ 12 + 14]/2  = 13   =  Q1

And then we do the same thing with the four data points to the right of Q2

These are  16    17.5 18   19

The median of these =  [ 17.5 + 18 ] / 2 =  17.75    =  Q3

So....the IQR   =  Q3 - Q1   =   4.5

Hope that helps

CPhill  Feb 7, 2019
#4
+484
+2

Oh okay, I get it. Thanks, CPhill!!!

awsometrunt14  Feb 8, 2019