That was my thought as well - there were two valid answers, and fixing neither of them on their own would have resolved the query for the correct intent.

One could assume that the data columns were integers purely because of the output format, however this can vary with options and the tools used.
However the formula was incorrect regardless of the data format.

So I got a "wrong answer" score despite picking up the fact that the formula was incorrect, I had to choose one of them but the law of 50/50 leapt in as usual 🙂