Translation:Fifty three women are reading the same book.
Fifty three women read the same book.
That's right if they read them every day or if it is universal rule and so on, but in any case it is not mistake, it is only the problem of specific connotation.
But take it easily - the creators of duolingo are only people and may have your own view on fifty women. Lucky men. They saw them all reading and it was miracle not usual thing. Be lucky too.