The probability of an outcome of a random phenomenon is
A) either 0 or 1, depending on whether or not the phenomenon can actually occur.
B) the proportion of a very long series of repetitions on which the outcome occurs.
C) the mean plus or minus two standard deviations.
D) another name for its expected value.
E) the confidence level.

Question

Quizplus · Accepted Answer

The definition of probability is the long-term proportion of times that an event will occur in repeated trials of a random phenomenon. Therefore, option B accurately defines probability. Option A is incorrect because an outcome cannot have a probability of 0 or 1 unless it is impossible or certain, respectively. Option C is incorrect because the mean and standard deviation are not necessarily related to probability. Option D is incorrect because expected value is a measure of central tendency, not probability. Option E is incorrect because confidence level is a term used in statistical inference, not probability.

The Probability of an Outcome of a Random Phenomenon Is