Probability Distributions

Probability Distributions

Discrete Random Variables

Expected Value

Variance and Standard Deviation​

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Multiple Select

Choose the correct examples of discrete variable.

• A film critic's rating of a film (0 - 4 stars)

• The sum of the numbers rolled on a pair of dice

• Time taken to commute to work

• Winning ticket number drawn from a raffle

• Amount of gasoline a car

Multiple Choice

Given a random variable X between 0 and 3, if P(0) = .15, P(1) = .2, P(2)= .3, P(3) =?

• 0.65

• 0.45

• 0.35

• 0.25

Multiple Choice

From the following Prob Dist, which of these is most likely the mean?

• 0.31

• 22

• 100

• 25

Multiple Choice

How to find the standard deviation of a random variable or SD (X)?

• Get the sum of (x multiplied by the probability of x

• The square root of variance (X)

• The expected value of X2 subtract the expected value of X, squared

• Get the sum of (x squared multiplied by the probability of x)

Multiple Choice

A Random Variable X can take only two values, 1 and 2P(1) = 0.8 and P(2) = 0.2. Calculate the Expected value of X.

• 0.5

• 1

• 1.2

• 1.5

Multiple Choice

A Random Variable X can take only two values, 1 and 2P(1) = 0.8 and P(2) = 0.2. Calculate the variance of X.

• 0.16

• 0.4

• 0.26

• 0.76

Multiple Choice

A cubical die is biased. The numbers one to five are equally likely to land face up, but six is twice as likely to land face up as each of the other numbers.If X is the score shown  on the uppermost face, calculate the expected value of X.

• 3

• 3 4/7

• 3 1/2

• 3 6/7

Multiple Choice

Two fair coins are tossed.If Y represents the number of tails, what is the Expected Value of Y?

• 0.5

• 1.5

• 1

• 2

Multiple Choice

• 1.1611

• 1.0775

• 1.0775

• 1.414