Expected Value and Fair Games

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

If the expected value is negative, are you expected to win?

• yes
• no

A coin is flipped 3 times. If you get tails once you get $5, tails twice you get $15, and tails on all three flips you get $40. What is the expected amount of money you will get?

• $12.50
• $5
• $7.50
• $10

Tags

CCSS.7.NS.A.3

Eva flips a coin. If she gets heads, she wins $4. If she gets tails, she loses $3. What is her expected value of a coin flip?

• $1

• $0.50

• -$0.50

• $0

Suppose you pay $1.00 to roll a fair die with the understanding you will get $3.00 back rolling a 4 or a 2, and nothing otherwise. Is this a fair game?

• yes

• no

A student group sells 500 raffle tickets for $2 each. At the drawing the top prize will be a gift certificate for $100. Second prize will be a $50 gift card and there will be five 3rd prizes, each a $20 gift card. Do you expect to win or lose (on average)? How much?

• lose an average of $5.50

• lose an average of $1.50

• win an average of $2.00

• lose an average of $10.00

Eva flips a coin. If she gets heads, she wins $4. If she gets tails, she loses $3. What is her expected value of a coin flip?

• $1

• $0.50

• -$0.50

• $0

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

• 1.75
• 1.84
• 2.00
• 2.50

You pick a card from a deck.  If you get a face card, you win $5.  If you get an ace, you win $30 plus an extra $60 for the ace of hearts.  For any other card you win nothing. Find the expected value you will win.

• $5.00
• $3.85
• $4.04
• $4.62

Number of Thunderstorms during August
Number of Storms    0     1      2      3
Probability               0.2   0.2   0.4   0.2
How many storms should we expect in August?

• 1.8
• 2.0
• 1.6
• 2.2