Hello, I'm new in the Math Forum

I'm not a native English speaker, so I apologize for any mistakes in advance.

This problem was in my Mathematics test:

My teacher says the answer is 30.A ship has disappeared in the ocean. We admit that the situation has been caused by any of the following equiprobable causes:

sinking

sequestration

destruction by storm

To each case, the probability of the rescuing team manages to rescue all the crewmembers alive is, respectively, 4/5, 3/5 and 7/10

1st question - [ bla bla bla]

2nd question - We now know that 14 crewmembers were saved and that the cause of the disappearance was not the storm. After all, how many crewmembers were in the aforesaid ship?

I say the question makes absolutely no sense, as all we know are the odds (conditioned for each cause) for all of the crewmembers to survive. 14/30 would be the propotion between the number of rescues with all people saved and the total number of rescues.

I tried to explain my view to her, but she says she doesn't understand my problem with this question... Am I crazy or is she the one who seriously needs holidays?