The local newspaper has letters to the editor from 20 people. If this number represents 8% of all of the newspaper's readers, how many readers does the newspaper have?

To find the interquartile range you will list the data in order from least to greatest.

Find the median (marked with the | - it is not one of the numbers).

Look at the left half the data and find the middle - lower quartile (underlined) and look at the right half of the data and find the middle - upper quartile

112, 119, 143, |  146, 152, 175

The distance from 119 to 152 is the IQR.  Subtract them to find the value,

152 - 119 = 33

The IQR is 33.