Math  /  Data & Statistics

QuestionA certain game involves tossing 3 fair coins, and it pays 99 \notin for 3 heads, 44 \notin for 2 heads, fand 22 \notin for 1 head. Is 44 \notin a fair price to pay to play this game? That is, does the 4ϕ4 \phi cost to play make the game fair?
The 4c4 c cost to play \square is not a fair price to pay because the expected winnings are \square 4. (Type an integer or a fraction. Simplify your answer.)

Studdy Solution

STEP 1

What is this asking? Is paying 44 cents a fair price for a game where you toss three coins and win $9\$9 cents for three heads, 44 cents for two heads, and 22 cents for one head? Watch out! Don't forget to consider all the possible outcomes when calculating the expected winnings!

STEP 2

1. Calculate probability of each outcome
2. Calculate expected winnings for each outcome
3. Calculate total expected winnings

STEP 3

Let's **start** by figuring out the probability of getting three heads.
Since each coin flip is independent, we *multiply* the probabilities of getting a head on each individual flip.
The probability of a head on a single fair coin toss is 12\frac{1}{2}.
So, the probability of three heads is 121212=18\frac{1}{2} \cdot \frac{1}{2} \cdot \frac{1}{2} = \frac{1}{8}.

STEP 4

Now, for two heads.
There are three ways to get two heads and one tail: HHT, HTH, or THH.
Each of these has a probability of 121212=18\frac{1}{2} \cdot \frac{1}{2} \cdot \frac{1}{2} = \frac{1}{8}.
Since there are **three** such combinations, the total probability of getting two heads is 318=383 \cdot \frac{1}{8} = \frac{3}{8}.

STEP 5

Similarly, for one head, there are three ways: HTT, THT, or TTH.
Each has a probability of 18\frac{1}{8}.
So, the total probability of getting one head is 318=383 \cdot \frac{1}{8} = \frac{3}{8}.

STEP 6

Finally, the probability of getting zero heads (all tails) is 121212=18\frac{1}{2} \cdot \frac{1}{2} \cdot \frac{1}{2} = \frac{1}{8}.

STEP 7

The **expected winnings** for each outcome are calculated by multiplying the probability of that outcome by the amount you win for that outcome.

STEP 8

For three heads, the expected winnings are 189=98\frac{1}{8} \cdot 9 = \frac{9}{8} cents.

STEP 9

For two heads, the expected winnings are 384=128\frac{3}{8} \cdot 4 = \frac{12}{8} cents.

STEP 10

For one head, the expected winnings are 382=68\frac{3}{8} \cdot 2 = \frac{6}{8} cents.

STEP 11

For zero heads, you win $0\$0, so the expected winnings are 180=0\frac{1}{8} \cdot 0 = 0 cents.

STEP 12

To find the **total expected winnings**, we add up the expected winnings for each outcome: 98+128+68+0=9+12+68=278\frac{9}{8} + \frac{12}{8} + \frac{6}{8} + 0 = \frac{9+12+6}{8} = \frac{27}{8} cents.

STEP 13

The expected winnings are 278\frac{27}{8} cents, which is 3.3753.375 cents.
Since this is less than the 44 cent cost to play, the 44 cent cost is *not* a fair price.

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