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Old 11-16-2008, 02:55 PM
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Default Discrete Probability Distributions

A multiple-choice examination has 15 questions. Each question has four possible answers of which only one is correct. The probability that by just guessing a student will get exactly 7 correct is?
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A_ n = \int D\mu \int D[X]exp\left(-\frac{1}{4\pi \alpha} \int \partial_z X_{\mu}(z,\bar{z})\partial_{\bar{z}}X^{\mu}(z,\bar{z})dz + i\sum_{i=1}^N k_{i \mu}X^{\mu}(z_i,\bar{z_i})\right)
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Old 11-16-2008, 03:07 PM
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{15 \choose 7}(s)^7(1-s)^{15-7}
Where s is the probability of success.
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Old 11-16-2008, 03:12 PM
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Thanks, and I assume that s would be 0.25 because of four possible choices and one correct answer.
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A_ n = \int D\mu \int D[X]exp\left(-\frac{1}{4\pi \alpha} \int \partial_z X_{\mu}(z,\bar{z})\partial_{\bar{z}}X^{\mu}(z,\bar{z})dz + i\sum_{i=1}^N k_{i \mu}X^{\mu}(z_i,\bar{z_i})\right)
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