Probability Question - Am I doing this problem right?

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What is the probability that a sheepdog performs at least $1$ of these tasks successfully?



My approach is to subtract the probability of performing at most $1$ of these tasks successfully from the probability of performing all $4$ tasks successfully.



$P(textfetch)=.9, P(textdrive)=.7, P(textherd)=.84, P(textseparate)=.75$.



The complement of these four probabilities is, $.1,.3,.16,$ and $,.25$, respectively.



So the probability that the sheepdog performs all four tasks successfully is simply, $(.9)(.7)(.84)(.75)$.



The probability that the sheepdog performs at most $1$ task successfully can be split into $4$ cases. Either the sheepdog performs the fetch task (and not the other 3) successfully, performs the drive task, performs the herd task, or performs the separate task.



This would look like:



$(.9)(.3)(.16)(.25)+(.1)(.7)(.16)(.25)+(.1)(.3)(.84)(.25)+(.1)(.3)(.16)(.75)$



Subtracting this from the case in which the sheepdog performs all four tasks would yield:



$(.9)(.7)(.84)(.75)-[(.9)(.3)(.16)(.25)+(.1)(.7)(.16)(.25)+(.1)(.3)(.84)(.25)+(.1)(.3)(.16)(.75)]$.



Is this correct?










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  • note: i would obviously simplify my answer at the end by multiplying all of the numbers out, i just want to see if this approach is correct...
    – rover2
    2 hours ago














up vote
2
down vote

favorite












enter image description here



What is the probability that a sheepdog performs at least $1$ of these tasks successfully?



My approach is to subtract the probability of performing at most $1$ of these tasks successfully from the probability of performing all $4$ tasks successfully.



$P(textfetch)=.9, P(textdrive)=.7, P(textherd)=.84, P(textseparate)=.75$.



The complement of these four probabilities is, $.1,.3,.16,$ and $,.25$, respectively.



So the probability that the sheepdog performs all four tasks successfully is simply, $(.9)(.7)(.84)(.75)$.



The probability that the sheepdog performs at most $1$ task successfully can be split into $4$ cases. Either the sheepdog performs the fetch task (and not the other 3) successfully, performs the drive task, performs the herd task, or performs the separate task.



This would look like:



$(.9)(.3)(.16)(.25)+(.1)(.7)(.16)(.25)+(.1)(.3)(.84)(.25)+(.1)(.3)(.16)(.75)$



Subtracting this from the case in which the sheepdog performs all four tasks would yield:



$(.9)(.7)(.84)(.75)-[(.9)(.3)(.16)(.25)+(.1)(.7)(.16)(.25)+(.1)(.3)(.84)(.25)+(.1)(.3)(.16)(.75)]$.



Is this correct?










share|cite|improve this question





















  • note: i would obviously simplify my answer at the end by multiplying all of the numbers out, i just want to see if this approach is correct...
    – rover2
    2 hours ago












up vote
2
down vote

favorite









up vote
2
down vote

favorite











enter image description here



What is the probability that a sheepdog performs at least $1$ of these tasks successfully?



My approach is to subtract the probability of performing at most $1$ of these tasks successfully from the probability of performing all $4$ tasks successfully.



$P(textfetch)=.9, P(textdrive)=.7, P(textherd)=.84, P(textseparate)=.75$.



The complement of these four probabilities is, $.1,.3,.16,$ and $,.25$, respectively.



So the probability that the sheepdog performs all four tasks successfully is simply, $(.9)(.7)(.84)(.75)$.



The probability that the sheepdog performs at most $1$ task successfully can be split into $4$ cases. Either the sheepdog performs the fetch task (and not the other 3) successfully, performs the drive task, performs the herd task, or performs the separate task.



This would look like:



$(.9)(.3)(.16)(.25)+(.1)(.7)(.16)(.25)+(.1)(.3)(.84)(.25)+(.1)(.3)(.16)(.75)$



Subtracting this from the case in which the sheepdog performs all four tasks would yield:



$(.9)(.7)(.84)(.75)-[(.9)(.3)(.16)(.25)+(.1)(.7)(.16)(.25)+(.1)(.3)(.84)(.25)+(.1)(.3)(.16)(.75)]$.



Is this correct?










share|cite|improve this question













enter image description here



What is the probability that a sheepdog performs at least $1$ of these tasks successfully?



My approach is to subtract the probability of performing at most $1$ of these tasks successfully from the probability of performing all $4$ tasks successfully.



$P(textfetch)=.9, P(textdrive)=.7, P(textherd)=.84, P(textseparate)=.75$.



The complement of these four probabilities is, $.1,.3,.16,$ and $,.25$, respectively.



So the probability that the sheepdog performs all four tasks successfully is simply, $(.9)(.7)(.84)(.75)$.



The probability that the sheepdog performs at most $1$ task successfully can be split into $4$ cases. Either the sheepdog performs the fetch task (and not the other 3) successfully, performs the drive task, performs the herd task, or performs the separate task.



This would look like:



$(.9)(.3)(.16)(.25)+(.1)(.7)(.16)(.25)+(.1)(.3)(.84)(.25)+(.1)(.3)(.16)(.75)$



Subtracting this from the case in which the sheepdog performs all four tasks would yield:



$(.9)(.7)(.84)(.75)-[(.9)(.3)(.16)(.25)+(.1)(.7)(.16)(.25)+(.1)(.3)(.84)(.25)+(.1)(.3)(.16)(.75)]$.



Is this correct?







probability combinatorics






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asked 2 hours ago









rover2

480110




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  • note: i would obviously simplify my answer at the end by multiplying all of the numbers out, i just want to see if this approach is correct...
    – rover2
    2 hours ago
















  • note: i would obviously simplify my answer at the end by multiplying all of the numbers out, i just want to see if this approach is correct...
    – rover2
    2 hours ago















note: i would obviously simplify my answer at the end by multiplying all of the numbers out, i just want to see if this approach is correct...
– rover2
2 hours ago




note: i would obviously simplify my answer at the end by multiplying all of the numbers out, i just want to see if this approach is correct...
– rover2
2 hours ago










2 Answers
2






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up vote
3
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The complement of at least $1$ is not at most $1$.



The complement is if none of the task is perform.



Hence just compute $$1-prod_i=1^4 (1-p_i)$$






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  • woowwwww...i cant believe i missed that. thank you ! i got it now
    – rover2
    2 hours ago

















up vote
1
down vote













By sheepdog, I assume you mean 'good sheepdog' as defined in the question. Let $X$ denote the number of things in the list satisfied. If you want the probability the at least one of the 4things listed is satisfied $P(Xgeq 1)$, you work it out by solving $ 1-P(X=0)$ This is equal to $1-(0.1)(0.3)(0.16)(0.25) = 0.9988$






share|cite|improve this answer








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    2 Answers
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    2 Answers
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    up vote
    3
    down vote













    The complement of at least $1$ is not at most $1$.



    The complement is if none of the task is perform.



    Hence just compute $$1-prod_i=1^4 (1-p_i)$$






    share|cite|improve this answer






















    • woowwwww...i cant believe i missed that. thank you ! i got it now
      – rover2
      2 hours ago














    up vote
    3
    down vote













    The complement of at least $1$ is not at most $1$.



    The complement is if none of the task is perform.



    Hence just compute $$1-prod_i=1^4 (1-p_i)$$






    share|cite|improve this answer






















    • woowwwww...i cant believe i missed that. thank you ! i got it now
      – rover2
      2 hours ago












    up vote
    3
    down vote










    up vote
    3
    down vote









    The complement of at least $1$ is not at most $1$.



    The complement is if none of the task is perform.



    Hence just compute $$1-prod_i=1^4 (1-p_i)$$






    share|cite|improve this answer














    The complement of at least $1$ is not at most $1$.



    The complement is if none of the task is perform.



    Hence just compute $$1-prod_i=1^4 (1-p_i)$$







    share|cite|improve this answer














    share|cite|improve this answer



    share|cite|improve this answer








    edited 2 hours ago

























    answered 2 hours ago









    Siong Thye Goh

    83.4k1456104




    83.4k1456104











    • woowwwww...i cant believe i missed that. thank you ! i got it now
      – rover2
      2 hours ago
















    • woowwwww...i cant believe i missed that. thank you ! i got it now
      – rover2
      2 hours ago















    woowwwww...i cant believe i missed that. thank you ! i got it now
    – rover2
    2 hours ago




    woowwwww...i cant believe i missed that. thank you ! i got it now
    – rover2
    2 hours ago










    up vote
    1
    down vote













    By sheepdog, I assume you mean 'good sheepdog' as defined in the question. Let $X$ denote the number of things in the list satisfied. If you want the probability the at least one of the 4things listed is satisfied $P(Xgeq 1)$, you work it out by solving $ 1-P(X=0)$ This is equal to $1-(0.1)(0.3)(0.16)(0.25) = 0.9988$






    share|cite|improve this answer








    New contributor




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





















      up vote
      1
      down vote













      By sheepdog, I assume you mean 'good sheepdog' as defined in the question. Let $X$ denote the number of things in the list satisfied. If you want the probability the at least one of the 4things listed is satisfied $P(Xgeq 1)$, you work it out by solving $ 1-P(X=0)$ This is equal to $1-(0.1)(0.3)(0.16)(0.25) = 0.9988$






      share|cite|improve this answer








      New contributor




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



















        up vote
        1
        down vote










        up vote
        1
        down vote









        By sheepdog, I assume you mean 'good sheepdog' as defined in the question. Let $X$ denote the number of things in the list satisfied. If you want the probability the at least one of the 4things listed is satisfied $P(Xgeq 1)$, you work it out by solving $ 1-P(X=0)$ This is equal to $1-(0.1)(0.3)(0.16)(0.25) = 0.9988$






        share|cite|improve this answer








        New contributor




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









        By sheepdog, I assume you mean 'good sheepdog' as defined in the question. Let $X$ denote the number of things in the list satisfied. If you want the probability the at least one of the 4things listed is satisfied $P(Xgeq 1)$, you work it out by solving $ 1-P(X=0)$ This is equal to $1-(0.1)(0.3)(0.16)(0.25) = 0.9988$







        share|cite|improve this answer








        New contributor




        Displayname 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






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        answered 2 hours ago









        Displayname

        963




        963




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        Displayname is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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        Displayname is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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