Translation:She is three times as strong as the boy.
the translation doesnt make sense. it means as strong as means they are have both the same strengh so i think the translation should be "she is three times stronger than". its one of those sentences that you shouldnt translate literally.
Haven't you heard someone say they're ten times as strong as someone before? I've heard it, I'm from England so I don't know if Americans use it (if you are American of course)
To be honest i dont recall having read or listened to "10 times as strong as", but lets say my memoriy is not my strongest attribute. I dont see the point in saying that you have 10 times the same strenght as someone, you could rather say you are 10 times stronger, it just seems more correct But then again English is not my mother tong, so maybe you are right