17. Swift et al. (A-13) conducted a study concerned with the presence of significant psychiatric illness in heterozygous carriers of the gene for the Wolfram syndrome.

According to the investigators, the Wolfram syndrome is an autosomal recessive neurodegenerative syndrome in which 25 percent of the individuals who are homozygous for the condition have severe psychiatric symptoms that lead to suicide attempts or psychiatric hospitalizations. Among the subjects studied were 543 blood relatives of patients with Wolfram syndrome. The following is a frequency distribution of the ages of these blood relatives:

Age Number 20-29 55 30-39 93 40-49 113 50-59 90 60-69 85 70-79 73 80-89 29 90-99 5 Total 543 SOURCE: Ronnie Gorman Swift, Diane 0. Perkins, Charles L. Chase, Debra B. Sadler, and Michael Swift, "Psychiatric Disorders in 36 Families With Wolfram Syndrome," American Journal of Psychiatry, 148 (1991), 775-779.

a. For these data construct a relative frequency distribution, a cumulative frequency distribution, and a cumulative relative frequency distribution.

b. Compute the mean, median, variance, and standard deviation. Use formulas for computing sample descriptive measures.