What is the interquartile range for the numbers 4,3,2,3,5,7,2,1

First organize numbers from left to right:
1,2,2,3,3,4,5,7
Then, divide into 4 groups (Quartiles):
1,2  2,3  3,4  5,7
Q3-Q1 is interquartile range
(3+4/2) - (1+2/2) = 3.5 - 1.5
Interquartile range is 2

The correct answer is: 2