Random Variable

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Random Variable
Message posted by Linda (via 152.163.197.58) on June 5, 2001 at 6:59 PM (ET)

On a multiple-choice test with 5 answers (one correct, 4 wrong) to each question, a student randomly selects an answer to each of 200 questions. Determine the mean and standard deviation for the random variable denoting the number of correct answers.

READERS RESPOND:
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Re: Random Variable
Message posted by JG (via 128.8.21.44) on June 5, 2001 at 10:16 PM (ET)

mean is 40 and SD is 5.66

Re: Random Variable
Message posted by nancy diehl (via 129.176.151.122) on June 6, 2001 at 2:38 PM (ET)

What you need to recognize is that this is a binomial distribution of 200 independent trials where the probability of getting a right answer is 1/5 or .20=20%.

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