14. John and Mary are planning to start a family. John was married once before, and he and his first wife had a child with cystic
fibrosis. The brother of his current wife, Mary, died of cystic fibrosis. What is the probability that John and Mary will have a
baby with cystic fibrosis? (Neither John, Mary, nor their parents have cystic fibrosis.)
(A)1/4
(B)1/6
(C)1/8
(D) 1/12
(E)1/16
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統計: A(74), B(33), C(36), D(4), E(7) #938809
統計: A(74), B(33), C(36), D(4), E(7) #938809
詳解 (共 3 筆)
#5941393
2/3×1/4=1/6
John的兒子有症狀->John 為Aa
Mary的哥哥有症狀->Mary可能為Aa or AA
兩人的兒子要有症狀=>須為Aa×Aa=aa(1/4)
John為Aa的可能性100%
Mary Aa的可能性為2/3
故2/3×1/4=1/6
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