I think that may be why I qualified my statement with the first word, technically.
Neither of the common Portuguese questions translates directly to, how old are you. But this is just part of learning/knowing another language. However, I think it can be helpful with comprehension to know the literal translations, even if they are not used.
Hi, basically both answers are correct in their "meaning". How old are you and what is your age both mean the same thing however; because we are learning Portuguese via translation, in my opinion; the most correct answer/translation to English is, "what is your age"; which is perfectly acceptable in English and is the closest accurate answer/translation.
Its difficult to show a rule on it. Basically: o que / o quê = what, qual = which. But there are exceptions... http://forum.wordreference.com/showthread.php?t=1700377
I can't tell you how many times I've had to play one of the phrases 5-6 times on the slow speed just to try and understand what the robot is saying. Especially when it is a phrase that I have never heard before, it can be very difficult to understand her. Sometimes I wish there were two voice recordings to choose from (male and female, for example) to give a bit more clarity in the recording. But I can understand why that's not really feasible on a free software.