Question

Can it be concluded that if there is a 50% chance of contracting a communicable disease through contact with an infected person, there would be a 100% chance of contracting the disease if 2 contacts were made with the infected person?

Answer 1

No it cannot be concluded.

Explanation:

The probability of getting the disease in the first attempt is 50%

The probability of getting the disease in the second attempt is 50%

Thus the probability of getting the disease in either of the turns is 50%+50%=100% (which may seem to be true)

BUT

The probability of not getting the disease in the first attempt is 50%

The probability of not getting the disease in the second attempt is 50%

Thus the probability of not getting the disease in either of the turns is 50%+50%=100% (which is also true for this case)

Thus the probability of getting the disease in either of the 2 contacts is still 50%