A researcher records the number of individual instruments identified by students listening to a piece of classical music.He splits the data into quartiles and reports that students correctly identified three instruments at the 25th percentile,five instruments at the 50th percentile,and eight instruments at the 75th percentile.What are the IQR and SIQR for these data?
A) the IQR is 3; the SIQR is 1.5
B) the IQR is 5; the SIQR is 5.0
C) the IQR is 5; the SIQR is 2.5
D) There is not enough information to answer this question.

Question

Quizplus · Accepted Answer

The IQR is the difference between the 75th and 25th percentiles, which is 8 - 3 = 5. 
The SIQR is half of the IQR, which is 5/2 = 2.5. 
Therefore, the correct option is C.

A Researcher Records the Number of Individual Instruments Identified by Students