Statistics, Chapter 8 HW

Which formula below gives the theoretical mean of a random variable "x"?

• Σ[x⋅P(x)]
• Σ(x)/n
• Σ(x)/N
• Σ[d²⋅P(x)]

Which formula below gives the theoretical variance of a random variable "x"?

• Σ[d²⋅P(x)]
• Σ[x⋅P(x)]
• Σ(x)/n
• Σ(x)/N

Find the mean of the probability distribution shown in the image.

• 11.61
• 1.30
• 1.14
• 12

Find the standard deviation of the probability distribution shown in the image.

• 11.61
• 1.30
• 1.14
• 12

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

Tags

CCSS.HSS.MD.A.3

CCSS.HSS.MD.A.2

CCSS.HSS.MD.B.5

There is a 20% chance of an earthquake somewhere in the state this year. If an earthquake does occur, the chance of an earthquake next year drops to 10%. However, if an earthquake does not occur this year, the chance of an earthquake next year rises to 25%.
Let x= number of years in the next two years that have earthquakes in the state.
Find E(x)

• 0.42
• 0.40
• 0.38
• 0.36

Tags

CCSS.HSS.MD.A.2

A type of game called a Martingale has a large probability of a small gain, and a small probability of a large loss.
Playing a round of a certain Martingale game will earn you a gain of $10 95% of the time, but there is a 5% chance of a $200 loss!
Over the long run, how much money will you lose per round playing this game?

• $0.50
• $90.50
• $10.95
• $5.00

Tags

CCSS.HSS.MD.B.5A

A fire company raffle sold 500 tickets to help raise money for a new truck. Each ticket was sold for $10. One ticket won a grand prize worth $200, and five other tickets won lesser prizes that were each worth $20.
What is the expected value of one of these raffle tickets?

• -$9.40
• -$1.20
• -$0.48
• -$0.60

Tags

CCSS.HSS.MD.B.5A

Review: There are 3 starters, 4 main courses and 2 desserts available at a restaurant. How many ways are there to have a set dinner with a starter, a main course and a dessert?

• 9
• 16
• 24
• 28

Review: A data set can have more than...

• Mean
• Median
• Mode
• Range