The data set in Table 1.20 lists all cases of Down syndrome in Victoria, Australia, from 1942 through 1957, as well as the number of births classified by the age of the mother (Andrews and Herzberg, 1985).

(a) Construct a relative frequency histogram for total number of births by age group.

(b) Construct a relative frequency histogram for number of mothers of Down syndrome patients by age group.

(c) Compare the shape of the two histograms. Does the shape of the histogram for Down syndrome suggest that age alone accounts for number of Down syndrome patients born?

(d) Construct a scatter diagramof totalnumber of births versusnumber ofmothers of Down syndrome. Does the scatter diagram support the conclusion in part (c)?