Pregnant women are screened for a birth defect called Down syndrome. Down syndrome babies are mentally and physically challenged. Some mothers choose to abort the fetus when they are certain that their baby will be born with the syndrome. The most common screening is maternal serum screening, a blood test that looks for markers in the blood to indicate whether the birth defect may occur. The false-positive and false-negative rates vary according to the age of the mother.

a. For each of the ages 25, 30, 35, 40, 45, and 49 determine the probability of Down syndrome if the maternity serum screening produces a positive result.
b. Repeat for a negativeresult.

Transcribed Image Text:

False- False- Mother's Positive Negative Age Under 30 30-34 35-37 Over 38 Rate Probability of Rate 04 082 178 .343 Down Syndrome 376 290 269 029 Age 25 30 35 40 45 49 1/1300 1/900 1/350 1/100 1/25 1/12 The probability that a baby has Down syndrome is primarily a