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What is the probability of guessing 70 out of 100 multiple choice questions correct when there are 4 choices per question?

  • math -

    prob of being right is 1/4
    prob of guessing wrong is 3/4

    so prob of guessing 70 out of 100 correct is
    C(100,70)*(1/4)^70*(3/4)^30
    = 3.763*10^-21

    we are dealing with very large and very small numbers here, and I had to "trust" my calculator.

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