The frequency distribution below shows the distribution for IQ scores for a random sample of 1000 adults. (Show all work. Just the answer, without supporting work, will receive no credit.)
IQ Scores frequency cumulative relative frequency
50 - 69 23
70 - 89 249
90 -109 .74
110 - 129
130 - 149 25
Total 1000
(a) Complete the frequency table with frequency and cumulative relative frequency. Express the cumulative relative frequency to three decimal places.
(b) What percentage of the adults in this sample has an IQ score between 90 and 129, inclusive?
(c) Which of the following IQ score groups does the median of this distribution belong to?
70 - 89, 90 - 109, or 110 - 129? Why?