Conflicting Probability Question (1 Viewer)

[Jacobagel]

This was a question in a biology exam at our school, where the teacher argues that the answer is 50%, whilst the students suggest it is 25%. I thought there was no better place to put the question here, and see what you all think the answer is. The question follows:

"A mum has a 50% chance of having a disease. If she has the disease, her child has a 50% chance of inheriting it from her mum. However, if the mum doesn't not have the disease, the child will not have the disease. What is the probability that the child has the disease?"

 

[HeroWise]

Id put 25 too lol

 

[fan96]

the teacher argues that the answer is 50%

What argument is this?

 

[aa180]

This was a question in a biology exam at our school, where the teacher argues that the answer is 50%, whilst the students suggest it is 25%. I thought there was no better place to put the question here, and see what you all think the answer is. The question follows:

"A mum has a 50% chance of having a disease. If she has the disease, her child has a 50% chance of inheriting it from her mum. However, if the mum doesn't not have the disease, the child will not have the disease. What is the probability that the child has the disease?"

 

[mathsbrain]

Is the formula you used the law of total probability? Is that in the syllabus?

 

[aa180]

Is the formula you used the law of total probability? Is that in the syllabus?

Yes, you are correct. I don't quite think it is in the syllabus, I just didn't see a way to answer the question without it

 

[zoeeoz18]

its 25% because 50% x 50% = 25%