Hijeck
AIPPG Experienced Senior Member
Joined: 02 Oct 2008
Posts: 521
19197 Credits
|
 Posted: Mon Nov 02, 2009 1:42 pm Post subject: The frequency of Tay-Sachs carriers among Ashkenazi Jews is |
|
|
The frequency of Tay-Sachs carriers among Ashkenazi Jews is 1/30. The frequency of Tay-Sachs carriers among whites of Western European descent is approximately 1/300. If a mother is an Ashkenazi Jew and a father is a white from Western Europe, what is the chance that a child of this union will have Tay-Sachs disease?
A. 1/120
B. 1/240
C. 1/3600
D. 1/9000
E. 1/36,000
|
|
Hijeck
AIPPG Experienced Senior Member
Joined: 02 Oct 2008
Posts: 521
19197 Credits
|
| Posted: Mon Nov 02, 2009 1:43 pm Post subject: |
|
|
| To determine the joint probability of two or more independent events, the product of their separate probabilities must be determined. If the parents were both Ashkenazi Jews, they would have a 1/30 chance of carrying an abnormal gene for Tay-Sachs disease; for each pregnancy, they would have a ½ chance of passing that gene along should they carry it. The probability that all of these four independent events would occur is 1/30 x ½ x 1/30 x ½ = 1/3600. The joint probability for a mother who is an Ashkenazi Jew and a father who is not is1/30 x ½ x 1/300 x ½ = 1/36,000.
|
|
