4.2 Discrete Random Variables

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

Tags

CCSS.HSS.MD.A.2

In a certain community, 30% of households have 1 child, 43% have 2 children, and 27% have 3 children. If a household is selected at random, what is the expected number of children in that household? HINT: A Probability table may be helpful.

• 2.00
• 2.13
• 1.97
• 1.27

Tags

CCSS.HSS.MD.A.2

Choose an American household at random. What is the expected number of cars for that household?

• 1.75
• 1.84
• 2.00
• 2.50

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CCSS.HSS.MD.A.2

A small store keeps track of the number X of customers that make a purchase during the first hour that the store is open each day. Based on the records, X has the following probability distribution. What is the average number of customers that the owner can expect to make a purchase in the first hour of opening?

• 0.2

• 1.4

• 2.0

• 3.0

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CCSS.HSS.MD.A.2

A game consists of rolling a colored die with three red sides, two green sides, and one blue side. A roll of a red loses. A roll of green pays $2.00. A roll of blue pays $5.00.   The charge to play the game is $2.00. What is the expected value

• $0
• -$0.50
• $.67
• $-1.50

Tags

CCSS.HSS.MD.B.5A

How many goals have you scored this year?

• continuous

• discrete

How long does the bus to Birchington take?

• continuous

• discrete

Is this a probability distribution?

• No, the sum of p(x) does not equal 1.

• Yes, all p(x) are between 0 and 1.

• No, all p(x) are not between 0 and 1.

• Yes, the sum p(x) is 1.

Tags

CCSS.HSS.MD.A.3

CCSS.HSS.MD.A.4

The table above shows a television station's advertisement sales. The distribution of sales for one 24-hour day is given. Solve for the standard deviation. Round to the nearest hundredth.

• 35.76

• 268.1

• 16.3

• 1279.35

What does a standard deviation of 0 mean?

• There is no spread of data

• The spread of data is close to the mean

• The data is more spread out from the mean

• There is no mean