You are correct. Mladá indicates that it is feminine. Masculine would be mladý in this instance.
‘...is he?’ got rejected (2017-09-18). First miss I’ve come across so far in what is pretty much a brand new course. Kudos, Czech team.
I may be wrong but I believe 'is he' is rejected because 'mlada' is feminine, implying you are asking about a female when followed me a non-gender-descriptive term like "je" for he/she. If it was "mlady" then he would be the correct term.
Jak mladá je?
Why "How old is she?" is wrong answer? Not sure that translation has to be literal.
How old is she?
Continue You used the wrong word. How young is she?
Because the Czech version too emphasizes the word "young" and isn't the general way to ask for one's age.