Option 1: 

After conception, a fetus can undergo genetic testing. Doctors can test for a range of genetic conditions, including Down Syndrome. Parents in different circumstances make different choices about whether to test. In some countries, the government regulates genetic testing.

Maternal age is the leading risk factor for whether a child will be born with Down Syndrome. According to the National Down Syndrome Society, an adult woman’s likelihood of having a child with Down Syndrome ranges from about 0.05% at age 20 to 10% at age 49. For this reason, doctors often recommend that older pregnant women undergo genetic testing to find out if their fetus could have this condition.

Which of the following is equivalent to 0.05% – 10%?

A. 1/5 – 1/20 

B.  1/5 – 1/2

C.  1/5 – 1/10

D.  1/2,000 – 1/10 

Option 2: 

A range of genetic tests can be done before conception, too. For example, some people who are thinking about having children are tested for a mutation in a gene known as the CFTR gene. This mutation can lead to cystic fibrosis, or CF. The CFTR gene helps regulate sweat, mucus, and digestive fluids. If one parent does NOT have the mutation, then the other parent does not need to get tested; in this circumstance, their children will not have CF. If each parent has one CFTR gene, each child they produce will have a 25% chance of having cystic fibrosis.

Mr. and Mrs. Stein both have one CFTR mutation. If they have two children, what are the chances that both children will develop CF?