BIO - Genetics

[belmont3]

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A certain autosomal recessive condition is seen in approximately 1 in every 50 people, but are symptom-free. If a male and a female possibly carry the gene, what is the probability that they have a diseased child?

a) 5%
b) 1%
c) 0.1%
d) 0.01%
e) 10%

The answer is D. However, the math explanation is not clear. Can you please explain to me in a better explanation how did we end up with 0.01% ?!!

Thank you!!

 

[LittleMo]

It says they possibly carry the gene, meaning they are both heterozygous. The punnet square would reveal that the probability of a diseased child is 0.25; also it says 1 in 50 people (2% or 0.02) are carriers, but symptom free. Since two people fit these conditions, the calculations are as follows:
(0.25)(0.02)(0.02)=0.0001 which is 0.01%