Translation:It takes half an hour to walk there.
Also, in the character-to-pronunciation matching tests, the English meanings should already be shown so that we can mentally associate the Chinese character with its possible meanings right there and then, helping in memorization. Currently, we'd find out the meanings of the individual characters (when we hover over them) only in the sentence translation tests.
There is a simple reason to that: characters have TONS of different meanings. You change the sentence, you change the meaning of the character. Sometimes you might know the meaning of one character alone, but then it gets associated with another one and a new meaning arises: 明天，聪明，明白，how are you supposed to associate 明 with one meaning? Let alone that you can deprive those characters of any meaning, for example in nouns (like 昆明, the city Kunming). And finally, you should have found out by now that most characters rarely ever come alone (good luck finding 明 alone) so why give the translation(s) to it when it is almost always associated with other characters? When I started learning Chinese, I was already in China, and my Chinese friends and coworkers quickly made me understand that I should almost never think about the meaning of a single isolated character. It's like almost all the words in Chinese are like "get" in English: get up? get down? get in? get out? get through? get mad? go get him? You can't translate "get" if you don't know what comes after/before. Chinese language is similar. It's a huuuuuuuuuuge get-like alphabet
While it makes sense for Duo to focus on teaching full words to beginners, it's also very beneficial to learn the meanings associated with single characters. Some people say if you see a new word and are familiar with each character, then it will be easier to figure out the full meaning on your own.
Anyone interested in learning the meanings associated with a single character should try Yellowbridge dictionary. For instance, 聪明 shows the 'word decomposition' or breakdown of each character. By clicking on a single character, you can also see the etymology tab.
It may not be practical for Duo to offer that level of detail, but some people do appreciate learning at a deeper level.
It is impossible to guess what philosophy of translation this site is using. Sometimes translations are very woodenly moved from Chinese to English. At other times they are massaged to make answers smoother in English. This makes translating very frustrating on this website, because there is often more than one correct way to translate what is written.
If "Walking there takes half an hour." is accepted, I think "Walking there requires half an hour." should also be accepted. "要" means "need" and "require" is a more natural synonym in this case. ("Walking there needs half an hour." sounds a bit strange, so I used "requires".)