Probability of sum 15 when roll 3rd dice, and first roll of 2 dice at least 10











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enter image description hereTwo dice have been thown, giving a total of at least 10.
What is the probability that the throw of a third die
will bring the total of the three numbers shown to 15 or higher?
I work out is 2/27. but physicsandmathstutor.com give a solution is 4/9.
i wander if you can help and explain in details. thanks










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  • Welcome to MSE. It will be more likely that you will get an answer if you show us that you made an effort. This should be added to the question rather than in the comments.
    – José Carlos Santos
    Nov 19 at 0:07






  • 1




    For example, how did you get $frac 2{27}$? Could you sketch your method?
    – lulu
    Nov 19 at 0:12










  • The answer must be at least $frac26$ since the third die being $5$ or $6$ would be sufficient in every case
    – Henry
    Nov 19 at 0:13















up vote
0
down vote

favorite












enter image description hereTwo dice have been thown, giving a total of at least 10.
What is the probability that the throw of a third die
will bring the total of the three numbers shown to 15 or higher?
I work out is 2/27. but physicsandmathstutor.com give a solution is 4/9.
i wander if you can help and explain in details. thanks










share|cite|improve this question









New contributor




Jan Jin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.




















  • Welcome to MSE. It will be more likely that you will get an answer if you show us that you made an effort. This should be added to the question rather than in the comments.
    – José Carlos Santos
    Nov 19 at 0:07






  • 1




    For example, how did you get $frac 2{27}$? Could you sketch your method?
    – lulu
    Nov 19 at 0:12










  • The answer must be at least $frac26$ since the third die being $5$ or $6$ would be sufficient in every case
    – Henry
    Nov 19 at 0:13













up vote
0
down vote

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up vote
0
down vote

favorite











enter image description hereTwo dice have been thown, giving a total of at least 10.
What is the probability that the throw of a third die
will bring the total of the three numbers shown to 15 or higher?
I work out is 2/27. but physicsandmathstutor.com give a solution is 4/9.
i wander if you can help and explain in details. thanks










share|cite|improve this question









New contributor




Jan Jin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











enter image description hereTwo dice have been thown, giving a total of at least 10.
What is the probability that the throw of a third die
will bring the total of the three numbers shown to 15 or higher?
I work out is 2/27. but physicsandmathstutor.com give a solution is 4/9.
i wander if you can help and explain in details. thanks







probability dice






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edited 2 days ago





















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asked Nov 19 at 0:04









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  • Welcome to MSE. It will be more likely that you will get an answer if you show us that you made an effort. This should be added to the question rather than in the comments.
    – José Carlos Santos
    Nov 19 at 0:07






  • 1




    For example, how did you get $frac 2{27}$? Could you sketch your method?
    – lulu
    Nov 19 at 0:12










  • The answer must be at least $frac26$ since the third die being $5$ or $6$ would be sufficient in every case
    – Henry
    Nov 19 at 0:13


















  • Welcome to MSE. It will be more likely that you will get an answer if you show us that you made an effort. This should be added to the question rather than in the comments.
    – José Carlos Santos
    Nov 19 at 0:07






  • 1




    For example, how did you get $frac 2{27}$? Could you sketch your method?
    – lulu
    Nov 19 at 0:12










  • The answer must be at least $frac26$ since the third die being $5$ or $6$ would be sufficient in every case
    – Henry
    Nov 19 at 0:13
















Welcome to MSE. It will be more likely that you will get an answer if you show us that you made an effort. This should be added to the question rather than in the comments.
– José Carlos Santos
Nov 19 at 0:07




Welcome to MSE. It will be more likely that you will get an answer if you show us that you made an effort. This should be added to the question rather than in the comments.
– José Carlos Santos
Nov 19 at 0:07




1




1




For example, how did you get $frac 2{27}$? Could you sketch your method?
– lulu
Nov 19 at 0:12




For example, how did you get $frac 2{27}$? Could you sketch your method?
– lulu
Nov 19 at 0:12












The answer must be at least $frac26$ since the third die being $5$ or $6$ would be sufficient in every case
– Henry
Nov 19 at 0:13




The answer must be at least $frac26$ since the third die being $5$ or $6$ would be sufficient in every case
– Henry
Nov 19 at 0:13










3 Answers
3






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up vote
0
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Hint: I suggest a Probability Tree with total values then if it is 15 or more as the second branch. Calculate the probabilities individually. This should help clear any doubt you have with your answer.






share|cite|improve this answer








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Anuj Doshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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    if you list all possible events is 16, over sample space 216 events. 16/216 = 2/27




    D1 D2 D3
    1 4 -> 6 => 5
    2 4 -> 6 => 6
    3 5 -> 5 => 5
    4 5 -> 5 => 6
    5 6 -> 4 => 5
    6 6 -> 4 => 6
    7 5 -> 6 => 4
    8 5 -> 6 => 5
    9 5 -> 6 => 6
    10 6 -> 5 => 4
    11 6 -> 5 => 5
    12 6 -> 5 => 6
    13 6 -> 6 => 3
    14 6 -> 6 => 4
    15 6 -> 6 => 5
    16 6 -> 6 => 6


    for people think use conditional probability, I think the wrong part is use probabilty 1/6 for two dice sum 10, applies to each event.






    share|cite|improve this answer








    New contributor




    Jan Jin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      Let $A$ be the event "total of the three numbers shown to 15 or higher", $B_1$ be the event "total of first two is 10", $B_2$ be the event "total of first two is 11", $B_3$ be the event "total of first two is 12". We have
      begin{align}
      P(B_1) = 3/6^2\
      P(B_2) = 2/6^2\
      P(B_3) = 1/6^2
      end{align}

      If $B$ is the event "total of first two is at least 10", then $P(B_1|B)=1/2$, $P(B_2|B)=1/3$ and $P(B_3|B)=1/6$. Finally
      begin{align}
      P(A|B)&=P(A|B_1,B)P(B_1|B)+P(A|B_2,B)P(B_2|B)+P(A|B_3,B)P(B_3|B)\
      &=1/3times1/2+1/2times1/3+2/3times1/6=4/9
      end{align}






      share|cite|improve this answer























      • I think B1 be the event "total of first two is 10" P(B1) = 3/(6x6) = 3/36 ?
        – Jan Jin
        2 days ago










      • yup that was a typo
        – dynamic89
        2 days ago











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      3 Answers
      3






      active

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      3 Answers
      3






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      active

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      active

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      up vote
      0
      down vote













      Hint: I suggest a Probability Tree with total values then if it is 15 or more as the second branch. Calculate the probabilities individually. This should help clear any doubt you have with your answer.






      share|cite|improve this answer








      New contributor




      Anuj Doshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.






















        up vote
        0
        down vote













        Hint: I suggest a Probability Tree with total values then if it is 15 or more as the second branch. Calculate the probabilities individually. This should help clear any doubt you have with your answer.






        share|cite|improve this answer








        New contributor




        Anuj Doshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
        Check out our Code of Conduct.




















          up vote
          0
          down vote










          up vote
          0
          down vote









          Hint: I suggest a Probability Tree with total values then if it is 15 or more as the second branch. Calculate the probabilities individually. This should help clear any doubt you have with your answer.






          share|cite|improve this answer








          New contributor




          Anuj Doshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
          Check out our Code of Conduct.









          Hint: I suggest a Probability Tree with total values then if it is 15 or more as the second branch. Calculate the probabilities individually. This should help clear any doubt you have with your answer.







          share|cite|improve this answer








          New contributor




          Anuj Doshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
          Check out our Code of Conduct.









          share|cite|improve this answer



          share|cite|improve this answer






          New contributor




          Anuj Doshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
          Check out our Code of Conduct.









          answered Nov 19 at 0:20









          Anuj Doshi

          11




          11




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          New contributor





          Anuj Doshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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          Anuj Doshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
          Check out our Code of Conduct.






















              up vote
              0
              down vote













              if you list all possible events is 16, over sample space 216 events. 16/216 = 2/27




              D1 D2 D3
              1 4 -> 6 => 5
              2 4 -> 6 => 6
              3 5 -> 5 => 5
              4 5 -> 5 => 6
              5 6 -> 4 => 5
              6 6 -> 4 => 6
              7 5 -> 6 => 4
              8 5 -> 6 => 5
              9 5 -> 6 => 6
              10 6 -> 5 => 4
              11 6 -> 5 => 5
              12 6 -> 5 => 6
              13 6 -> 6 => 3
              14 6 -> 6 => 4
              15 6 -> 6 => 5
              16 6 -> 6 => 6


              for people think use conditional probability, I think the wrong part is use probabilty 1/6 for two dice sum 10, applies to each event.






              share|cite|improve this answer








              New contributor




              Jan Jin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
              Check out our Code of Conduct.






















                up vote
                0
                down vote













                if you list all possible events is 16, over sample space 216 events. 16/216 = 2/27




                D1 D2 D3
                1 4 -> 6 => 5
                2 4 -> 6 => 6
                3 5 -> 5 => 5
                4 5 -> 5 => 6
                5 6 -> 4 => 5
                6 6 -> 4 => 6
                7 5 -> 6 => 4
                8 5 -> 6 => 5
                9 5 -> 6 => 6
                10 6 -> 5 => 4
                11 6 -> 5 => 5
                12 6 -> 5 => 6
                13 6 -> 6 => 3
                14 6 -> 6 => 4
                15 6 -> 6 => 5
                16 6 -> 6 => 6


                for people think use conditional probability, I think the wrong part is use probabilty 1/6 for two dice sum 10, applies to each event.






                share|cite|improve this answer








                New contributor




                Jan Jin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.




















                  up vote
                  0
                  down vote










                  up vote
                  0
                  down vote









                  if you list all possible events is 16, over sample space 216 events. 16/216 = 2/27




                  D1 D2 D3
                  1 4 -> 6 => 5
                  2 4 -> 6 => 6
                  3 5 -> 5 => 5
                  4 5 -> 5 => 6
                  5 6 -> 4 => 5
                  6 6 -> 4 => 6
                  7 5 -> 6 => 4
                  8 5 -> 6 => 5
                  9 5 -> 6 => 6
                  10 6 -> 5 => 4
                  11 6 -> 5 => 5
                  12 6 -> 5 => 6
                  13 6 -> 6 => 3
                  14 6 -> 6 => 4
                  15 6 -> 6 => 5
                  16 6 -> 6 => 6


                  for people think use conditional probability, I think the wrong part is use probabilty 1/6 for two dice sum 10, applies to each event.






                  share|cite|improve this answer








                  New contributor




                  Jan Jin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                  Check out our Code of Conduct.









                  if you list all possible events is 16, over sample space 216 events. 16/216 = 2/27




                  D1 D2 D3
                  1 4 -> 6 => 5
                  2 4 -> 6 => 6
                  3 5 -> 5 => 5
                  4 5 -> 5 => 6
                  5 6 -> 4 => 5
                  6 6 -> 4 => 6
                  7 5 -> 6 => 4
                  8 5 -> 6 => 5
                  9 5 -> 6 => 6
                  10 6 -> 5 => 4
                  11 6 -> 5 => 5
                  12 6 -> 5 => 6
                  13 6 -> 6 => 3
                  14 6 -> 6 => 4
                  15 6 -> 6 => 5
                  16 6 -> 6 => 6


                  for people think use conditional probability, I think the wrong part is use probabilty 1/6 for two dice sum 10, applies to each event.







                  share|cite|improve this answer








                  New contributor




                  Jan Jin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                  Check out our Code of Conduct.









                  share|cite|improve this answer



                  share|cite|improve this answer






                  New contributor




                  Jan Jin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                  Check out our Code of Conduct.









                  answered 2 days ago









                  Jan Jin

                  11




                  11




                  New contributor




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                  New contributor





                  Jan Jin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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                  Jan Jin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                  Check out our Code of Conduct.






















                      up vote
                      0
                      down vote













                      Let $A$ be the event "total of the three numbers shown to 15 or higher", $B_1$ be the event "total of first two is 10", $B_2$ be the event "total of first two is 11", $B_3$ be the event "total of first two is 12". We have
                      begin{align}
                      P(B_1) = 3/6^2\
                      P(B_2) = 2/6^2\
                      P(B_3) = 1/6^2
                      end{align}

                      If $B$ is the event "total of first two is at least 10", then $P(B_1|B)=1/2$, $P(B_2|B)=1/3$ and $P(B_3|B)=1/6$. Finally
                      begin{align}
                      P(A|B)&=P(A|B_1,B)P(B_1|B)+P(A|B_2,B)P(B_2|B)+P(A|B_3,B)P(B_3|B)\
                      &=1/3times1/2+1/2times1/3+2/3times1/6=4/9
                      end{align}






                      share|cite|improve this answer























                      • I think B1 be the event "total of first two is 10" P(B1) = 3/(6x6) = 3/36 ?
                        – Jan Jin
                        2 days ago










                      • yup that was a typo
                        – dynamic89
                        2 days ago















                      up vote
                      0
                      down vote













                      Let $A$ be the event "total of the three numbers shown to 15 or higher", $B_1$ be the event "total of first two is 10", $B_2$ be the event "total of first two is 11", $B_3$ be the event "total of first two is 12". We have
                      begin{align}
                      P(B_1) = 3/6^2\
                      P(B_2) = 2/6^2\
                      P(B_3) = 1/6^2
                      end{align}

                      If $B$ is the event "total of first two is at least 10", then $P(B_1|B)=1/2$, $P(B_2|B)=1/3$ and $P(B_3|B)=1/6$. Finally
                      begin{align}
                      P(A|B)&=P(A|B_1,B)P(B_1|B)+P(A|B_2,B)P(B_2|B)+P(A|B_3,B)P(B_3|B)\
                      &=1/3times1/2+1/2times1/3+2/3times1/6=4/9
                      end{align}






                      share|cite|improve this answer























                      • I think B1 be the event "total of first two is 10" P(B1) = 3/(6x6) = 3/36 ?
                        – Jan Jin
                        2 days ago










                      • yup that was a typo
                        – dynamic89
                        2 days ago













                      up vote
                      0
                      down vote










                      up vote
                      0
                      down vote









                      Let $A$ be the event "total of the three numbers shown to 15 or higher", $B_1$ be the event "total of first two is 10", $B_2$ be the event "total of first two is 11", $B_3$ be the event "total of first two is 12". We have
                      begin{align}
                      P(B_1) = 3/6^2\
                      P(B_2) = 2/6^2\
                      P(B_3) = 1/6^2
                      end{align}

                      If $B$ is the event "total of first two is at least 10", then $P(B_1|B)=1/2$, $P(B_2|B)=1/3$ and $P(B_3|B)=1/6$. Finally
                      begin{align}
                      P(A|B)&=P(A|B_1,B)P(B_1|B)+P(A|B_2,B)P(B_2|B)+P(A|B_3,B)P(B_3|B)\
                      &=1/3times1/2+1/2times1/3+2/3times1/6=4/9
                      end{align}






                      share|cite|improve this answer














                      Let $A$ be the event "total of the three numbers shown to 15 or higher", $B_1$ be the event "total of first two is 10", $B_2$ be the event "total of first two is 11", $B_3$ be the event "total of first two is 12". We have
                      begin{align}
                      P(B_1) = 3/6^2\
                      P(B_2) = 2/6^2\
                      P(B_3) = 1/6^2
                      end{align}

                      If $B$ is the event "total of first two is at least 10", then $P(B_1|B)=1/2$, $P(B_2|B)=1/3$ and $P(B_3|B)=1/6$. Finally
                      begin{align}
                      P(A|B)&=P(A|B_1,B)P(B_1|B)+P(A|B_2,B)P(B_2|B)+P(A|B_3,B)P(B_3|B)\
                      &=1/3times1/2+1/2times1/3+2/3times1/6=4/9
                      end{align}







                      share|cite|improve this answer














                      share|cite|improve this answer



                      share|cite|improve this answer








                      edited 2 days ago

























                      answered Nov 19 at 1:58









                      dynamic89

                      38418




                      38418












                      • I think B1 be the event "total of first two is 10" P(B1) = 3/(6x6) = 3/36 ?
                        – Jan Jin
                        2 days ago










                      • yup that was a typo
                        – dynamic89
                        2 days ago


















                      • I think B1 be the event "total of first two is 10" P(B1) = 3/(6x6) = 3/36 ?
                        – Jan Jin
                        2 days ago










                      • yup that was a typo
                        – dynamic89
                        2 days ago
















                      I think B1 be the event "total of first two is 10" P(B1) = 3/(6x6) = 3/36 ?
                      – Jan Jin
                      2 days ago




                      I think B1 be the event "total of first two is 10" P(B1) = 3/(6x6) = 3/36 ?
                      – Jan Jin
                      2 days ago












                      yup that was a typo
                      – dynamic89
                      2 days ago




                      yup that was a typo
                      – dynamic89
                      2 days ago










                      Jan Jin is a new contributor. Be nice, and check out our Code of Conduct.










                       

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