Applications with Standard Normal Distribution — Quiz
Question 2 • Mathematics III
The probability that a random variable is greater than or equal to z standard deviations from the mean in a standard normal distribution is p percent What can be said with certainty about the probability that the random variable is less than or equal to negative z standard deviations from the mean?
Answer
A
The probability is equal to p percent .
B
The probability is less than p percent .
C
The probability is not equal to p percent .
D
The probability is greater than p percent .
Explanation
The standard normal distribution is symmetric about its mean, 0. Values at least z standard deviations above the mean have the same probability as values at least z standard deviations below it. Therefore, the probability that the variable is less than or equal to −z standard deviations from the mean is also p percent: choice A.
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