Hypothesis Testing: condition to reject the null hypothesis

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Here is a question from a statistics textbook, the (c) question asks the condition to reject the null hypothesis. And the answer is to consider whether the probability for 3 or fewer people supporting the candidate is less than 5%. And my question is: why don't we just consider the probability for 3 people supporting the candidate and compare it to 5%, why using the probability for 3 or fewer people supporting the candidate? Thanks for any hints.

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