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Our professor gave this question as assignment, My question is does this question have all information needed to solve it? I asked her and she said it has all information but still I cannot figure out how I can solve it with just knowing the probability of using debit card in supermarket. Can someone please provide me a tip on how I can solve this question with this information or is it solvable?

According to a recent Interact survey, 28% of consumers use their debit cards in supermarkets. Find the probability that they use debit cards in only other stores or not at all.

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    This is hard to understand. Maybe you just mean that $72\%$ do not use their debit cards in supermarkets. Is that possible? – 2017-02-10
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    Draw a Venn diagram. One circle for "consumers who use debit cards in supermarkets". Another circle for "consumers who use debit cards only in non-supermarket stores, or not at all". Which areas of the diagram can possibly contain any people? – 2017-02-10
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    The question is clearly flawed, but since it's so _badly_ flawed, it's very likely that you didn't write it down correctly. Was it a printed question, or did you copy it from a question written on the board? – 2017-02-10
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    @quasi Its a printed question and that's all information provided – 2017-02-10
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    @HenningMakholm I just know the probability of customers using their debit cards in super market and no other information. How can I draw Vein diagram for customers using their debit cards in non-supermarket stores? – 2017-02-10
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    Then it's the teacher's fault. To make sure, can you post an image of the actual assignment sheet? – 2017-02-10
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    If the problem you posted is exactly what was assigned, don't bother with it. Wait until the teacher shows a "solution", and get back to us. – 2017-02-10
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    What course is it for? – 2017-02-10
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    @quasi probability and statistics course – 2017-02-10
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    @quasi Does it mean finding probability of not using in supermarket $(1-P(s))$? – 2017-02-10
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    The problem is just gibberish. Pure and simple. I am slightly appalled that problem was designed by a professor. – 2017-02-10

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The intended answer is mostly likely $72\%$. This is because to say that a consumer uses his/her debit cards "in only other stores or not at all" is logically equivalent to saying that he/she does not use his/her debit cards in supermarkets. So if $28\%$ of consumers do use their debit cards in supermarkets, then $72\%$ do not.

That said, the problem strikes me as not well worded. In giving the answer of $72\%$, I am assuming that what's meant by "the probability that they use debit cards..." is the probability that a randomly selected individual consumer uses his/her debit cards only in other stores or not at all. As stated, however, it's asking about the probability that an entire collection of consumers use their debit cards in a certain way. Whether you read the "they" as referring to the entire set of consumers, or just to the $28\%$ who use them at supermarkets (as quasi's answer does), the answer is $0$. It's possible the person writing the question really meant it this way, as quasi suggests; I think it's more likely they were just a bit sloppy in their wording. I know I sometimes am.

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    That makes more sense than my interpretation. With your interpretation, there is at least some math value, not just a grammar-based trick.. I think I'll delete my answer. – 2017-02-10
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    the problem doesn't say that 28% of consumers use their cards in the supermarket... it says that the result of a survey was 28%. – 2017-02-10
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    @SlugPue, I'm afraid I don't understand what you're getting at. How does the distinction you're making affect the interpretation of the problem? – 2017-02-10