I have a probability of $frac{24}{800000}$ to win with one lottery ticket. What if I buy two tickets?
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Assuming there's a lottery with 800,000 tickets and 24 of these tickets contain a win, my chance to win (if I buy only one ticket) is $frac{24}{800,000}$ or $frac{1}{33,333.overline{3}}$, right?
But what are my chances to win if I buy two tickets?
probability
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add a comment |
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Assuming there's a lottery with 800,000 tickets and 24 of these tickets contain a win, my chance to win (if I buy only one ticket) is $frac{24}{800,000}$ or $frac{1}{33,333.overline{3}}$, right?
But what are my chances to win if I buy two tickets?
probability
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HInt: compute the probability of NOT winning.
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– leonbloy
Dec 1 '16 at 16:19
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$33000$ is a really poor approximation to $100000/3$.
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– TonyK
Dec 1 '16 at 16:20
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@TonyK: Oh yeah. Obviously it's 33,333.$overline{3}$
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– 4242
Dec 1 '16 at 16:25
add a comment |
$begingroup$
Assuming there's a lottery with 800,000 tickets and 24 of these tickets contain a win, my chance to win (if I buy only one ticket) is $frac{24}{800,000}$ or $frac{1}{33,333.overline{3}}$, right?
But what are my chances to win if I buy two tickets?
probability
$endgroup$
Assuming there's a lottery with 800,000 tickets and 24 of these tickets contain a win, my chance to win (if I buy only one ticket) is $frac{24}{800,000}$ or $frac{1}{33,333.overline{3}}$, right?
But what are my chances to win if I buy two tickets?
probability
probability
edited Dec 1 '16 at 16:33
4242
asked Dec 1 '16 at 16:14
42424242
84
84
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HInt: compute the probability of NOT winning.
$endgroup$
– leonbloy
Dec 1 '16 at 16:19
$begingroup$
$33000$ is a really poor approximation to $100000/3$.
$endgroup$
– TonyK
Dec 1 '16 at 16:20
$begingroup$
@TonyK: Oh yeah. Obviously it's 33,333.$overline{3}$
$endgroup$
– 4242
Dec 1 '16 at 16:25
add a comment |
$begingroup$
HInt: compute the probability of NOT winning.
$endgroup$
– leonbloy
Dec 1 '16 at 16:19
$begingroup$
$33000$ is a really poor approximation to $100000/3$.
$endgroup$
– TonyK
Dec 1 '16 at 16:20
$begingroup$
@TonyK: Oh yeah. Obviously it's 33,333.$overline{3}$
$endgroup$
– 4242
Dec 1 '16 at 16:25
$begingroup$
HInt: compute the probability of NOT winning.
$endgroup$
– leonbloy
Dec 1 '16 at 16:19
$begingroup$
HInt: compute the probability of NOT winning.
$endgroup$
– leonbloy
Dec 1 '16 at 16:19
$begingroup$
$33000$ is a really poor approximation to $100000/3$.
$endgroup$
– TonyK
Dec 1 '16 at 16:20
$begingroup$
$33000$ is a really poor approximation to $100000/3$.
$endgroup$
– TonyK
Dec 1 '16 at 16:20
$begingroup$
@TonyK: Oh yeah. Obviously it's 33,333.$overline{3}$
$endgroup$
– 4242
Dec 1 '16 at 16:25
$begingroup$
@TonyK: Oh yeah. Obviously it's 33,333.$overline{3}$
$endgroup$
– 4242
Dec 1 '16 at 16:25
add a comment |
1 Answer
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Your chances to win at least once are roughly twice as high if you buy two tickets. Not exactly twice, because there is a very small chance both tickets will win, but this is small enough to ignore in an approximation.
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So that would mean the chance that I will win is now roughly $frac{1}{16,666}$? And if I buy 10 tickets, will it be $frac{1}{3,333}$? That doesn't sound right to me.
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– 4242
Dec 1 '16 at 16:30
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That is, roughly, correct. However, if you buy 10 tickets, the probability of more than one victory from those 10 becomes much larger, so it's actually significantly less than $frac{1}{3,333}$.
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– vadim123
Dec 1 '16 at 16:35
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@4242 the exact calculation can be done via routine counting methods. If we want the probability of not winning after having bought $k$ different lottery tickets it will be $frac{binom{800000-24}{k}}{binom{800000}{k}}$ where $binom{n}{r}$ is the binomial coefficient $frac{n!}{r!(n-r)!}$. The probability of winning at least once will be one minus that amount. For ten tickets that evaluates to approximately $0.0003$, similar to $1/3333$ but not exactly.
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– JMoravitz
Dec 1 '16 at 16:44
add a comment |
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1 Answer
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1 Answer
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$begingroup$
Your chances to win at least once are roughly twice as high if you buy two tickets. Not exactly twice, because there is a very small chance both tickets will win, but this is small enough to ignore in an approximation.
$endgroup$
$begingroup$
So that would mean the chance that I will win is now roughly $frac{1}{16,666}$? And if I buy 10 tickets, will it be $frac{1}{3,333}$? That doesn't sound right to me.
$endgroup$
– 4242
Dec 1 '16 at 16:30
$begingroup$
That is, roughly, correct. However, if you buy 10 tickets, the probability of more than one victory from those 10 becomes much larger, so it's actually significantly less than $frac{1}{3,333}$.
$endgroup$
– vadim123
Dec 1 '16 at 16:35
$begingroup$
@4242 the exact calculation can be done via routine counting methods. If we want the probability of not winning after having bought $k$ different lottery tickets it will be $frac{binom{800000-24}{k}}{binom{800000}{k}}$ where $binom{n}{r}$ is the binomial coefficient $frac{n!}{r!(n-r)!}$. The probability of winning at least once will be one minus that amount. For ten tickets that evaluates to approximately $0.0003$, similar to $1/3333$ but not exactly.
$endgroup$
– JMoravitz
Dec 1 '16 at 16:44
add a comment |
$begingroup$
Your chances to win at least once are roughly twice as high if you buy two tickets. Not exactly twice, because there is a very small chance both tickets will win, but this is small enough to ignore in an approximation.
$endgroup$
$begingroup$
So that would mean the chance that I will win is now roughly $frac{1}{16,666}$? And if I buy 10 tickets, will it be $frac{1}{3,333}$? That doesn't sound right to me.
$endgroup$
– 4242
Dec 1 '16 at 16:30
$begingroup$
That is, roughly, correct. However, if you buy 10 tickets, the probability of more than one victory from those 10 becomes much larger, so it's actually significantly less than $frac{1}{3,333}$.
$endgroup$
– vadim123
Dec 1 '16 at 16:35
$begingroup$
@4242 the exact calculation can be done via routine counting methods. If we want the probability of not winning after having bought $k$ different lottery tickets it will be $frac{binom{800000-24}{k}}{binom{800000}{k}}$ where $binom{n}{r}$ is the binomial coefficient $frac{n!}{r!(n-r)!}$. The probability of winning at least once will be one minus that amount. For ten tickets that evaluates to approximately $0.0003$, similar to $1/3333$ but not exactly.
$endgroup$
– JMoravitz
Dec 1 '16 at 16:44
add a comment |
$begingroup$
Your chances to win at least once are roughly twice as high if you buy two tickets. Not exactly twice, because there is a very small chance both tickets will win, but this is small enough to ignore in an approximation.
$endgroup$
Your chances to win at least once are roughly twice as high if you buy two tickets. Not exactly twice, because there is a very small chance both tickets will win, but this is small enough to ignore in an approximation.
answered Dec 1 '16 at 16:26
vadim123vadim123
76.4k897191
76.4k897191
$begingroup$
So that would mean the chance that I will win is now roughly $frac{1}{16,666}$? And if I buy 10 tickets, will it be $frac{1}{3,333}$? That doesn't sound right to me.
$endgroup$
– 4242
Dec 1 '16 at 16:30
$begingroup$
That is, roughly, correct. However, if you buy 10 tickets, the probability of more than one victory from those 10 becomes much larger, so it's actually significantly less than $frac{1}{3,333}$.
$endgroup$
– vadim123
Dec 1 '16 at 16:35
$begingroup$
@4242 the exact calculation can be done via routine counting methods. If we want the probability of not winning after having bought $k$ different lottery tickets it will be $frac{binom{800000-24}{k}}{binom{800000}{k}}$ where $binom{n}{r}$ is the binomial coefficient $frac{n!}{r!(n-r)!}$. The probability of winning at least once will be one minus that amount. For ten tickets that evaluates to approximately $0.0003$, similar to $1/3333$ but not exactly.
$endgroup$
– JMoravitz
Dec 1 '16 at 16:44
add a comment |
$begingroup$
So that would mean the chance that I will win is now roughly $frac{1}{16,666}$? And if I buy 10 tickets, will it be $frac{1}{3,333}$? That doesn't sound right to me.
$endgroup$
– 4242
Dec 1 '16 at 16:30
$begingroup$
That is, roughly, correct. However, if you buy 10 tickets, the probability of more than one victory from those 10 becomes much larger, so it's actually significantly less than $frac{1}{3,333}$.
$endgroup$
– vadim123
Dec 1 '16 at 16:35
$begingroup$
@4242 the exact calculation can be done via routine counting methods. If we want the probability of not winning after having bought $k$ different lottery tickets it will be $frac{binom{800000-24}{k}}{binom{800000}{k}}$ where $binom{n}{r}$ is the binomial coefficient $frac{n!}{r!(n-r)!}$. The probability of winning at least once will be one minus that amount. For ten tickets that evaluates to approximately $0.0003$, similar to $1/3333$ but not exactly.
$endgroup$
– JMoravitz
Dec 1 '16 at 16:44
$begingroup$
So that would mean the chance that I will win is now roughly $frac{1}{16,666}$? And if I buy 10 tickets, will it be $frac{1}{3,333}$? That doesn't sound right to me.
$endgroup$
– 4242
Dec 1 '16 at 16:30
$begingroup$
So that would mean the chance that I will win is now roughly $frac{1}{16,666}$? And if I buy 10 tickets, will it be $frac{1}{3,333}$? That doesn't sound right to me.
$endgroup$
– 4242
Dec 1 '16 at 16:30
$begingroup$
That is, roughly, correct. However, if you buy 10 tickets, the probability of more than one victory from those 10 becomes much larger, so it's actually significantly less than $frac{1}{3,333}$.
$endgroup$
– vadim123
Dec 1 '16 at 16:35
$begingroup$
That is, roughly, correct. However, if you buy 10 tickets, the probability of more than one victory from those 10 becomes much larger, so it's actually significantly less than $frac{1}{3,333}$.
$endgroup$
– vadim123
Dec 1 '16 at 16:35
$begingroup$
@4242 the exact calculation can be done via routine counting methods. If we want the probability of not winning after having bought $k$ different lottery tickets it will be $frac{binom{800000-24}{k}}{binom{800000}{k}}$ where $binom{n}{r}$ is the binomial coefficient $frac{n!}{r!(n-r)!}$. The probability of winning at least once will be one minus that amount. For ten tickets that evaluates to approximately $0.0003$, similar to $1/3333$ but not exactly.
$endgroup$
– JMoravitz
Dec 1 '16 at 16:44
$begingroup$
@4242 the exact calculation can be done via routine counting methods. If we want the probability of not winning after having bought $k$ different lottery tickets it will be $frac{binom{800000-24}{k}}{binom{800000}{k}}$ where $binom{n}{r}$ is the binomial coefficient $frac{n!}{r!(n-r)!}$. The probability of winning at least once will be one minus that amount. For ten tickets that evaluates to approximately $0.0003$, similar to $1/3333$ but not exactly.
$endgroup$
– JMoravitz
Dec 1 '16 at 16:44
add a comment |
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$begingroup$
HInt: compute the probability of NOT winning.
$endgroup$
– leonbloy
Dec 1 '16 at 16:19
$begingroup$
$33000$ is a really poor approximation to $100000/3$.
$endgroup$
– TonyK
Dec 1 '16 at 16:20
$begingroup$
@TonyK: Oh yeah. Obviously it's 33,333.$overline{3}$
$endgroup$
– 4242
Dec 1 '16 at 16:25