Final answer:
The standard deviation of a probability distribution measures how far the outcomes are from the mean. To find the standard deviation, calculate the variance first.
Step-by-step explanation:
The standard deviation of a probability distribution measures how far the outcomes of a statistical experiment are from the mean of the distribution. To find the standard deviation, you need to first calculate the variance.
To calculate the variance, you need to find each deviation from the expected value (mean), square it, multiply it by its probability, and add the products. Then, take the square root of the variance to find the standard deviation.
So, the correct answer to the question is A) Variance.