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## AP®︎/College Statistics

### Course: AP®︎/College Statistics>Unit 8

Lesson 2: Mean and standard deviation of random variables

# Standard deviation of a discrete random variable

You might need: Calculator

## Problem

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.
$0$$1$$2$
$P\left(X\right)$$0.09$$0.42$$0.49$
Given that ${\mu }_{X}=1.4$ makes, find the standard deviation of the number of shots that Anasia makes.
Round your answer to two decimal places.
${\sigma }_{X}\approx$
shots
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