One multiple choice question has 4 choices to choose from. Students must choose 2 correct answers from the 4 choices in order to pass. What is the probability of passing this question?


closed as off-topic by Em., Watson, colormegone, JKnecht, gebruiker Apr 20 '16 at 9:22

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There are $\binom{4}{2}=6$ unordered pairs of two choices. If the student chooses at random, each of these pairs is equally probable, so the probability of choosing the correct pair is $1/6$.

  • $\begingroup$ what would I enter into x, numtrial and p if I were to work out the probability on the calculator? $\endgroup$ – Annalisa Apr 20 '16 at 5:24
  • $\begingroup$ Doing that kind of calculation would assume you already know the probability. For example, if you set $x=10$, $p=1/6$, $n=25$, the calculator would give the probability of getting exactly 10 questions right on a test with 25 of such questions. $\endgroup$ – Funktorality Apr 20 '16 at 5:28

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