Question

The probability that a woman exposed to German measles will contract the disease is 0.2. if exposed to risk while pregnant, the probability is 0.1 that the child will suffer from a particular serious birth defect. Otherwise, the probability of such a defect is only 0.01. A child was born with this birth defect. What is the probability that the mother suffered from German measles while pregnant?
The probability that a woman exposed to German measles will contract the disease is 0.2. if exposed to risk while pregnant, the probability is 0.1 that the child will suffer from a particular serious birth defect. Otherwise, the probability of such a defect is only 0.01. A child was born with this birth defect. What is the probability that the mother suffered from German measles while pregnant?
@Mathematics

Answer 1

Baby has it - > chance it got it without the mum having it is 0.01
Chance the mum had it has to be 1 - 0.01 = 0.99

Answer 2

the answer key says the answer is .7143

Answer 3

The key point is that the probability of a defect is 0.1 if the mother is exposed, but not infected. If the mother is exposed her chance of getting infected is 0.2.

Answer 4

I still dont get what to do...

It sounds like "the child has the birth defect, thus the mother must have had the disease and therefore the probability is 1"