[student95]

I want to say that I've been studying Japanese for 3 years (and still am)　in response to the question 'how long have you been studying Japanese?

Would the question be どのぐらい日本語を勉強していまか。 or どのぐらい日本語を勉強していましたか。

Likewise, would this answer make sense?
日本語を三年ぐらい勉強していました。　(As I want to say I have been studying and not that I have studied)
or　日本語を三年間ぐらい勉強していました。