Is a probability distribution defined if the only possible values of a random variable are 0, 1, 2, 3, and P(0) = P(1) = P(2) = P(3) = 0.25?
Yes. The sum of all probabilities is equal to 1. This is a uniform distribution
There are 100 questions on a test with possible answers a-e and only one choice being correct for each question. What is the mean & S.D. of question a student could randomly answer correct on the test?
Mean: 20 Standard deviation = 4
If boys and girls are equally likely, groups of 400 births have a mean of 200 girls and a standard deviation of 10 girls. Is 232 girls in 400 births an unusually high number?
Yes. The value given in higher than two standard deviations away from the mean.
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