A researcher gives IQ tests to a large group of adults, and discovers that the
mean, median and mode all equal 100. The highest score in the group was 130
and the lowest was 70. Between IQ's of 75 and 125, 80% of the group was found, and 50% were found between IQ's of 90 and 110. The shape of the graphed distribution was mesokurtic.
-The interquartile range was equal to
A) 60
B) 50
C) 20
D) 0

Question

A researcher gives IQ tests to a large group of adults, and discovers that the 
mean, median and mode all equal 100.  The highest score in the group was 130 
and the lowest was 70.  Between IQ's of 75 and 125, 80% of the group was found,  and 50% were found between IQ's of 90 and 110.  The shape of the graphed  distribution was mesokurtic.     
-The interquartile range was equal to
A) 60
B) 50
C) 20
D) 0

Quizplus · Accepted Answer

The interquartile range (IQR) is the difference between the 75th percentile (Q3) and the 25th percentile (Q1) of the data. Given that 50% of the group's IQ scores are between 90 and 110, this range represents the middle 50% of the data, or the IQR. Therefore, the IQR is 110 - 90 = 20.

A Researcher Gives IQ Tests to a Large Group of Adults