Working with the Variance of a Discrete Random Variable
Use the following formula for the variance of a discrete random variable X as needed to answer the following problems (round each answer to two decimal places):
If the variance of a discrete random variable X is 3, what is the standard deviation of X?
The standard deviation is the square root of the variance, so if the variance of X is 3, the standard deviation of X is
(rounded to two decimal places).
If the standard deviation of X is 0.65, what is the variance of X?
The variance is the square of the standard deviation, so if the standard deviation of X is 0.65, the variance of X is (0.65)2 = 0.4225. Rounded to two decimal places, the answer is 0.42.
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