Translation:I don't understand this question.
Why does it say "这一题问题“？ Is "题" the classifier for "问题"？Why add the 一 then? Wouldn't it be possible to just say "这题问题"？
For me, the classifier is 条 or 个 (Traditional 條, 個), and for questions in a test/exam it tends to be 条; So I would say, 这一条问题，这两条问题, etc.; As shorter equivalents I would also say 这一题，这两题 (which is the typical phrase structure for classifiers), but I would not say 这一题问题, 这两题问题, and have not heard other people saying like that.
I am not sure if that is wrong.
I think of a similar example. We can call a table of guests in a restaurant 这一桌客人，那一桌客人; similarly for a table of food 这一桌食物. However, this never applies to other cases and we rarely would say table is a classifier. It is also not correct to say in Chinese 这一桌桌子. Has Duo failed here? Idk, but it is likely...
这一题问题 translates to "this one question." The 一 kind of emphasizes the specificity and can be omitted.
So 题 is the classifier for question? And 这一 just means "this one"? As in 这两只猫 "these two cats"? Then I wonder why Duolingo spends the grammar section explaining "to understand", but not this new piece of grammar....
I don't understand this problem - was marked incorrect. Can someone fluent in English and Chinese tell me if there is a difference between question and problem in Chinese? Can 问题 be both? 谢谢。
问题 means both problem and question. There are other words for each, such as 难题 for problem and 疑问 for question, but 问题 is always a good, hassle free choice.
I think the issue is on 题 in 这一题. This word only refers to a structured question, usually written, in test, exam or other assessments. As far as I know we don't usually call an exam question a problem (I remember I saw Problem 1, Problem 2 in my exam though.) If you are sure this is correct in English, you should report it as a valid answer.
Yes, "problem" and "question" are both equally valid ways to refer to an exam question in english.
"Math problem" is a term that was used when I was in high school.
I think math is the only context where this was used though. Adults are less likely to answer math questions than other types of questions, so I think this synonym would be infrequently heard in adult conversation.