Genetic counselors work with pregnant women (usually women at high risk of fetal abnormalities) and hypothesize that about one-half of all abnormalities are trisomy 21, one-third are trisomy 18, and the remainder are trisomy 13. (Trisomy indicates three copies of a particular chromosome). To test the hypothesis, a sample of 200 pregnant women who deliver babies with abnormalities are studied. The specific abnormalities are recorded and are summarized below. Base on the data, is the assumption regarding the distribution of abnormalities appropriate? Test it at 5% significance level.

Trisomy 21. Trisomy 18. Trisomy 13. Total

Number of women 120 80 40 240