A Researcher Gives IQ Tests to a Large Group of Adults

Multiple Choice

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 interdecile range was equal to

A) 60
B) 50
C) 20
D) 0