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DIA [1.3K]
3 years ago
13

You have 4 cards, 2 black and 2 red. You play a game where during each round you draw a card. If it's black, you lose a point. I

f it's red, you gain a point. You can chose to stop at any time. What's the expected value of this game
Mathematics
1 answer:
sineoko [7]3 years ago
8 0

Answer: The expected value of this game is 2/3

Step-by-step explanation:

Give that

If it's black, you lose a point. If it's red, you gain a point. 

And then you can stop at any time. But you should never stop when you are losing because that can guarantee 0 by drawing all the cards.

Assuming you should stop after three cards when you are +2.

The only question is whether to draw if you are +1 on the first draw.

If you draw red first, You have 1/3 chance of drawing red again and this will give you +2 points

1/3 chance of drawing two blacks and earn zero point, chance of drawing black-red and earn +1. This gives +1, so it doesn't matter whether you draw or not.

From the beginning, If you draw red (probability 1/2 you end +1. If you draw black and then draw two reds (probability 1/6 you end +1) Otherwise you break even with probability 1/3. Overall, the value is 2/3

You might be interested in
What is the smallest integer k>2000 such that both 17k/66 and 13k/105} are terminating decimals?
Dvinal [7]

17k/66 and 13k/105 must reduce to fractions with a denominator that only consists of powers of 2 or 5.

For example, some fractions with terminating decimals are

1/2 = 0.5

1/4 = 1/2² = 0.25

1/5 = 0.2

1/8 = 1/2³ = 0.125

1/10 = 1/(2•5) = 0.1

1/16 = 1/2⁴ = 0.0625

and so on, while some fractions with non-terminating decimals have denominators that include factors other than 2 or 5, like

1/3 = 0.333…

1/6 = 1/(2•3) = 0.1666…

1/7 = 0.142857…

1/9 = 1/3² = 0.111…

1/11 = 0.09…

1/12 = 1/(2²•3) = 0.8333…

etc.

Since 66 = 2•3•11, we need 17k to have a factorization that eliminates both 3 and 11.

Similarly, since 105 = 3•5•7, we need 13k to eliminate the factors of 3 and 7.

In other words, 17k must be divisible by both 3 and 11, and 13k must be divisible by both 3 and 7. But 13 and 17 are both prime, so it's just k that must be divisible by 3, 7, and 11. These three numbers are relatively prime, so the least positive k that meets the conditions is LCM(2, 7, 11) = 231, and thus k can be any multiple of 231.

If you're familiar with modular arithmetic, this is the same as solving for k such that

13k ≡ 0 (mod 3)

17k ≡ 0 (mod 3)

17k ≡ 0 (mod 7)

13k ≡ 0 (mod 11)

and the Chinese remainder theorem says that k = 231n solves the system of congruences, where n is any integer.

Now it's just a matter of finding the smallest multiple of 231 that's larger than 2000, which easily done by observing

2000 = 8•231 + 152

and so k = 9•231 = 2079.

3 0
2 years ago
I'm stuck :/ help hurry​
Free_Kalibri [48]

Answer: i think A is negative -2 and B is -19 hope this help im not a hundred percent sure if i got it wrong please let know.

Step-by-step explanation:

4 0
3 years ago
I have been struggling at this please help
Taya2010 [7]

Answer:

21

Step-by-step explanation:

I shall change the pictures to letters

a + a + b = 40 --(1)

b - c = 7 --(2)

c + a = 19 --(3)

a - c + b = ?

From (1):

2a + b = 40

b = 40 - 2a --(4)

From (2):

b = 7 + c --(5)

Sub (4) into (5):

40 - 2a = 7 + c

c = 33 - 2a --(6)

Sub (6) into (3):

33 - 2a + a = 19

a = 14

Sub a = 14 into (4) and (6):

b = 40 - 2(14) = 12

c = 33 - 2(14) = 5

therefore, a - c + b = 14 - 5 + 12 = 21

Topic: simultaneous equations

If you would like to venture further into mathematics, you can check out my Instagram page (learntionary) where I post notes and mathematics tips. Thanks!

5 0
3 years ago
Haos dog ate 40 cns of dog food in 31 day. how many cans should hao buy to feed his dog in 6 days
Crank
The answer is 8. 40 / 31 = 1.29032258. Multiply that by 6 and you have 7.74193548. Round up because you can't buy 7.7 cans of dog food.
7 0
3 years ago
Kwans The Kenningy account balance was $20 his ending balance is zero dollars what integer represents the changing in his accoun
77julia77 [94]

The integer number that represents the changing in his account balance from beginning to end is of -20.

<h3>Which numbers belong to the set of integer numbers?</h3>

Non-decimal numbers, either positive or negative numbers, also zero, belong to the set, which can be represented by:

Z = {..., -3, -2, -1, 0, 1, 2, 3, ...}

A change can be represented by the <u>final value subtracted by the initial value</u>. For this problem, we have that:

  • The initial balance is of $20.
  • The final balance is of $0.

Hence the change in the balance is:

0 - 20 = -20.

And the integer is -20.

More can be learned about integer numbers are brainly.com/question/17405059

#SPJ1

6 0
1 year ago
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