Biased dice probability question Announcing the arrival of Valued Associate #679: Cesar Manara Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)Probability of dice thrownDice and probabilityDetermine whether the dice is biased based on 10 rollsProbability of events with biased diceProbability of biased diceProbability on biased diceProbability of rolling 2 and 3 numbers in a sequence when rolling 3, 6 sided diceDice probability helpProbability of an “at least” QuestionProbability of biased die.
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Biased dice probability question
Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)Probability of dice thrownDice and probabilityDetermine whether the dice is biased based on 10 rollsProbability of events with biased diceProbability of biased diceProbability on biased diceProbability of rolling 2 and 3 numbers in a sequence when rolling 3, 6 sided diceDice probability helpProbability of an “at least” QuestionProbability of biased die.
$begingroup$
A biased six sided dice is rolled twice. Show that the probability that the two results are the same is at least $frac16$.
(Hint: $(p_1 − a)^2 + . . . + (p_6 − a)^2 ≥ 0$ and choose suitable
$p_1, . . . , p_6$, a.)
probability
New contributor
$endgroup$
add a comment |
$begingroup$
A biased six sided dice is rolled twice. Show that the probability that the two results are the same is at least $frac16$.
(Hint: $(p_1 − a)^2 + . . . + (p_6 − a)^2 ≥ 0$ and choose suitable
$p_1, . . . , p_6$, a.)
probability
New contributor
$endgroup$
$begingroup$
Hint: First try to show that if a coin is flipped twice, the probability that the two results are the same is at least $1/2$. This will help you figure out what to choose as $a$.
$endgroup$
– Lorenzo
10 mins ago
add a comment |
$begingroup$
A biased six sided dice is rolled twice. Show that the probability that the two results are the same is at least $frac16$.
(Hint: $(p_1 − a)^2 + . . . + (p_6 − a)^2 ≥ 0$ and choose suitable
$p_1, . . . , p_6$, a.)
probability
New contributor
$endgroup$
A biased six sided dice is rolled twice. Show that the probability that the two results are the same is at least $frac16$.
(Hint: $(p_1 − a)^2 + . . . + (p_6 − a)^2 ≥ 0$ and choose suitable
$p_1, . . . , p_6$, a.)
probability
probability
New contributor
New contributor
edited 20 mins ago
mathpadawan
2,019422
2,019422
New contributor
asked 23 mins ago
mandymandy
211
211
New contributor
New contributor
$begingroup$
Hint: First try to show that if a coin is flipped twice, the probability that the two results are the same is at least $1/2$. This will help you figure out what to choose as $a$.
$endgroup$
– Lorenzo
10 mins ago
add a comment |
$begingroup$
Hint: First try to show that if a coin is flipped twice, the probability that the two results are the same is at least $1/2$. This will help you figure out what to choose as $a$.
$endgroup$
– Lorenzo
10 mins ago
$begingroup$
Hint: First try to show that if a coin is flipped twice, the probability that the two results are the same is at least $1/2$. This will help you figure out what to choose as $a$.
$endgroup$
– Lorenzo
10 mins ago
$begingroup$
Hint: First try to show that if a coin is flipped twice, the probability that the two results are the same is at least $1/2$. This will help you figure out what to choose as $a$.
$endgroup$
– Lorenzo
10 mins ago
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
Let $p_i$ be the probability of rolling $i$. Then $sum_i=1^6 p_i = 1$.
By Cauchy-Schwarz inequality,
$$beginalign*
left(sum_i=1^6 1^2right) left(sum_i=1^6 p_i^2right) &ge
left(sum_i=1^6 1p_iright)^2\
6left(sum_i=1^6 p_i^2right) &ge 1\
sum_i=1^6 p_i^2 &ge frac16endalign*$$
Equality holds when all the $p_i$ are the same, i.e. when the die is unbiased.
$endgroup$
add a comment |
Your Answer
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1 Answer
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$begingroup$
Let $p_i$ be the probability of rolling $i$. Then $sum_i=1^6 p_i = 1$.
By Cauchy-Schwarz inequality,
$$beginalign*
left(sum_i=1^6 1^2right) left(sum_i=1^6 p_i^2right) &ge
left(sum_i=1^6 1p_iright)^2\
6left(sum_i=1^6 p_i^2right) &ge 1\
sum_i=1^6 p_i^2 &ge frac16endalign*$$
Equality holds when all the $p_i$ are the same, i.e. when the die is unbiased.
$endgroup$
add a comment |
$begingroup$
Let $p_i$ be the probability of rolling $i$. Then $sum_i=1^6 p_i = 1$.
By Cauchy-Schwarz inequality,
$$beginalign*
left(sum_i=1^6 1^2right) left(sum_i=1^6 p_i^2right) &ge
left(sum_i=1^6 1p_iright)^2\
6left(sum_i=1^6 p_i^2right) &ge 1\
sum_i=1^6 p_i^2 &ge frac16endalign*$$
Equality holds when all the $p_i$ are the same, i.e. when the die is unbiased.
$endgroup$
add a comment |
$begingroup$
Let $p_i$ be the probability of rolling $i$. Then $sum_i=1^6 p_i = 1$.
By Cauchy-Schwarz inequality,
$$beginalign*
left(sum_i=1^6 1^2right) left(sum_i=1^6 p_i^2right) &ge
left(sum_i=1^6 1p_iright)^2\
6left(sum_i=1^6 p_i^2right) &ge 1\
sum_i=1^6 p_i^2 &ge frac16endalign*$$
Equality holds when all the $p_i$ are the same, i.e. when the die is unbiased.
$endgroup$
Let $p_i$ be the probability of rolling $i$. Then $sum_i=1^6 p_i = 1$.
By Cauchy-Schwarz inequality,
$$beginalign*
left(sum_i=1^6 1^2right) left(sum_i=1^6 p_i^2right) &ge
left(sum_i=1^6 1p_iright)^2\
6left(sum_i=1^6 p_i^2right) &ge 1\
sum_i=1^6 p_i^2 &ge frac16endalign*$$
Equality holds when all the $p_i$ are the same, i.e. when the die is unbiased.
answered 9 mins ago
peterwhypeterwhy
12.3k21229
12.3k21229
add a comment |
add a comment |
mandy is a new contributor. Be nice, and check out our Code of Conduct.
mandy is a new contributor. Be nice, and check out our Code of Conduct.
mandy is a new contributor. Be nice, and check out our Code of Conduct.
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$begingroup$
Hint: First try to show that if a coin is flipped twice, the probability that the two results are the same is at least $1/2$. This will help you figure out what to choose as $a$.
$endgroup$
– Lorenzo
10 mins ago