Variance

Concept Quizzes

Variance - Definition
Variance - Properties
Standard Deviation
Covariance
Covariance - Properties

Variance - Definition

What is the variance of the following probability distribution: $\begin{array}{c}&P(X = -1) = 0.5, &P(X = 0) = 0.2, &P( X = 1) = 0.3 ?\end{array}$

2.76 3.76 0.76 1.76

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When all values of a dataset are doubled, what happens to the variance?

The variance is doubled The variance stays constant The variance is quadrupled The variance is halved

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You throw a coin twice. The prize is $50$ dollars if it lands heads, and $4$ dollars if it is tails. If $X$ is the total prize you will end up receiving, then what is the variance of $X ?$

1098 1058 1078 1068

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The probability distribution of a random variable $X$ is $\begin{array}{c}&P(X = 1) = a, &P(X = 2) = b, &P( X = 3) = 0.4. \end{array}$ If $a \cdot b=0.05$ and $a \geq b,$ then what is the variance of $X?$

1.89 4.89 0.89 2.89

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The probability distribution of a random variable $X$ is $\begin{array}{c}&P(X = 1) = 0.1, &P(X = 2) = 0.2, &P( X = 3) = a.\end{array}$ What is the variance of $X?$

1.44 2.44 0.44 4.44

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