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Standard deviation of a discrete random variable

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Anasia is a basketball player who regularly shoots sets of 2 free-throws. Suppose that each shot has probability 0.7 of being made, and the results of the shots are independent.
The table below displays the probability distribution of X, the number of shots that Anasia makes in a set of 2 attempts.
X=# of makes012
Given that μX=1.4 makes, find the standard deviation of the number of shots that Anasia makes.
Round your answer to two decimal places.
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi