Q6.2 Distributions and Expected Value

Classify: The numbers of cheeseburgers a fast-food restaurant serves each day

• Discrete

• Continuous

Which one of the following is a discrete random variable?

• Sam's height

• Sam weight

• Time Sam's runs the 110 m hurdles

• Amount of Sam's brothers and sisters

Classify: Height of a plant measured each day for 30 days.

• Discrete

• Continuous

Classify: The time it takes for a light bulb to burn out.

• Discrete

• Continuous

Is this a probability distribution?

• No

• Yes

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CCSS.HSS.MD.A.3

CCSS.HSS.MD.A.4

Is this a probability distribution?

• No
• Yes

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CCSS.HSS.MD.A.3

CCSS.HSS.MD.A.4

• Yes, because all of the probabilities are between 0 and 1 inclusive and the sum of all the probabilities is 1.
• No, all probabilities are not be between 0 and 1 inclusive
• No, the sum of all the probabilities is not 1.
• Yes, because the distribution is symmetric

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CCSS.7.SP.C.7B

• Yes, because all of the probabilities are between 0 and 1 inclusive and the sum of all the probabilities is 1.
• No, all probabilities are not be between 0 and 1 inclusive
• No, the sum of all the probabilities is not 1.
• Yes, because the distribution is symmetric

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CCSS.HSS.MD.A.3

CCSS.HSS.MD.A.4

A stockbroker estimates that at the end of the year, there is a 40% chance a stock will be worth $50, a 35% chance it will be worth $60 and a 25% chance it will be worth $70.
What expected value does this broker assign to this stock's end-of-the-year price?

• $58.50
• $60.00
• $62.50
• $65.00

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CCSS.HSS.MD.A.2

Given the probability model in the table below, what is the expected value of the random variable?
  X        50          20        5
P(X)     0.1         0.3      0.6

• 14
• 4.67
• 5
• 7.5

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CCSS.HSS.MD.A.2