Penalty score probability












0












$begingroup$



A footballer has a $0.8$ chance of scoring a penalty. How many
penalties does he need to take to score at least two times with a
$0.9$ probability?




I tried the negative binomial method ($r=2$), so that becomes $binom{m-1}{1}cdot 0.8^2cdot 0.2^{m-2}$. Or should I use hypergeometrical?










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$endgroup$












  • $begingroup$
    What are your thoughts? I don´t think that you get an answer if you don´t show a minimum of effort. See also here: How to ask a good question.
    $endgroup$
    – callculus
    Jan 27 at 17:01












  • $begingroup$
    The answer is $4$. However, if you want a more detailed answer you should put a little effort into your question.
    $endgroup$
    – Nathanael Skrepek
    Jan 27 at 17:08












  • $begingroup$
    No, hypergeometric distribution is not right. But why you don´t use the binomial distribution? And you can use the converse probability. $P(Xgeq 2)=1-P(X=1)-P(X=0)geq 0.9$, where $Xsim Bin(n, 0.8)$ Note that the inequality cannot be solved algebraically. Just try out some values for $n$.
    $endgroup$
    – callculus
    Jan 27 at 17:21


















0












$begingroup$



A footballer has a $0.8$ chance of scoring a penalty. How many
penalties does he need to take to score at least two times with a
$0.9$ probability?




I tried the negative binomial method ($r=2$), so that becomes $binom{m-1}{1}cdot 0.8^2cdot 0.2^{m-2}$. Or should I use hypergeometrical?










share|cite|improve this question











$endgroup$












  • $begingroup$
    What are your thoughts? I don´t think that you get an answer if you don´t show a minimum of effort. See also here: How to ask a good question.
    $endgroup$
    – callculus
    Jan 27 at 17:01












  • $begingroup$
    The answer is $4$. However, if you want a more detailed answer you should put a little effort into your question.
    $endgroup$
    – Nathanael Skrepek
    Jan 27 at 17:08












  • $begingroup$
    No, hypergeometric distribution is not right. But why you don´t use the binomial distribution? And you can use the converse probability. $P(Xgeq 2)=1-P(X=1)-P(X=0)geq 0.9$, where $Xsim Bin(n, 0.8)$ Note that the inequality cannot be solved algebraically. Just try out some values for $n$.
    $endgroup$
    – callculus
    Jan 27 at 17:21
















0












0








0





$begingroup$



A footballer has a $0.8$ chance of scoring a penalty. How many
penalties does he need to take to score at least two times with a
$0.9$ probability?




I tried the negative binomial method ($r=2$), so that becomes $binom{m-1}{1}cdot 0.8^2cdot 0.2^{m-2}$. Or should I use hypergeometrical?










share|cite|improve this question











$endgroup$





A footballer has a $0.8$ chance of scoring a penalty. How many
penalties does he need to take to score at least two times with a
$0.9$ probability?




I tried the negative binomial method ($r=2$), so that becomes $binom{m-1}{1}cdot 0.8^2cdot 0.2^{m-2}$. Or should I use hypergeometrical?







probability






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 27 at 17:32









callculus

18.6k31428




18.6k31428










asked Jan 27 at 16:57









NiccoNicco

12




12












  • $begingroup$
    What are your thoughts? I don´t think that you get an answer if you don´t show a minimum of effort. See also here: How to ask a good question.
    $endgroup$
    – callculus
    Jan 27 at 17:01












  • $begingroup$
    The answer is $4$. However, if you want a more detailed answer you should put a little effort into your question.
    $endgroup$
    – Nathanael Skrepek
    Jan 27 at 17:08












  • $begingroup$
    No, hypergeometric distribution is not right. But why you don´t use the binomial distribution? And you can use the converse probability. $P(Xgeq 2)=1-P(X=1)-P(X=0)geq 0.9$, where $Xsim Bin(n, 0.8)$ Note that the inequality cannot be solved algebraically. Just try out some values for $n$.
    $endgroup$
    – callculus
    Jan 27 at 17:21




















  • $begingroup$
    What are your thoughts? I don´t think that you get an answer if you don´t show a minimum of effort. See also here: How to ask a good question.
    $endgroup$
    – callculus
    Jan 27 at 17:01












  • $begingroup$
    The answer is $4$. However, if you want a more detailed answer you should put a little effort into your question.
    $endgroup$
    – Nathanael Skrepek
    Jan 27 at 17:08












  • $begingroup$
    No, hypergeometric distribution is not right. But why you don´t use the binomial distribution? And you can use the converse probability. $P(Xgeq 2)=1-P(X=1)-P(X=0)geq 0.9$, where $Xsim Bin(n, 0.8)$ Note that the inequality cannot be solved algebraically. Just try out some values for $n$.
    $endgroup$
    – callculus
    Jan 27 at 17:21


















$begingroup$
What are your thoughts? I don´t think that you get an answer if you don´t show a minimum of effort. See also here: How to ask a good question.
$endgroup$
– callculus
Jan 27 at 17:01






$begingroup$
What are your thoughts? I don´t think that you get an answer if you don´t show a minimum of effort. See also here: How to ask a good question.
$endgroup$
– callculus
Jan 27 at 17:01














$begingroup$
The answer is $4$. However, if you want a more detailed answer you should put a little effort into your question.
$endgroup$
– Nathanael Skrepek
Jan 27 at 17:08






$begingroup$
The answer is $4$. However, if you want a more detailed answer you should put a little effort into your question.
$endgroup$
– Nathanael Skrepek
Jan 27 at 17:08














$begingroup$
No, hypergeometric distribution is not right. But why you don´t use the binomial distribution? And you can use the converse probability. $P(Xgeq 2)=1-P(X=1)-P(X=0)geq 0.9$, where $Xsim Bin(n, 0.8)$ Note that the inequality cannot be solved algebraically. Just try out some values for $n$.
$endgroup$
– callculus
Jan 27 at 17:21






$begingroup$
No, hypergeometric distribution is not right. But why you don´t use the binomial distribution? And you can use the converse probability. $P(Xgeq 2)=1-P(X=1)-P(X=0)geq 0.9$, where $Xsim Bin(n, 0.8)$ Note that the inequality cannot be solved algebraically. Just try out some values for $n$.
$endgroup$
– callculus
Jan 27 at 17:21












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