Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    11
    ReputationRep:
    guys here in part C .. i know its a conditional probability but how do we find the numerator?? (the intersection)
    Name:  vvv.PNG
Views: 26
Size:  16.0 KB
    • Study Helper
    Offline

    13
    (Original post by pondsteps)
    guys here in part C .. i know its a conditional probability but how do we find the numerator?? (the intersection)
    Well what scenarios/combinations result in the die being rolled twice and the final score being three?
    • Thread Starter
    Offline

    11
    ReputationRep:
    (Original post by ghostwalker)
    Well what scenarios/combinations result in the die being rolled twice and the final score being three?
    P(T=3) intersection die rolled twice / P die rolled twice

    i mean how do i find the intersection??
    • Study Helper
    Offline

    13
    (Original post by pondsteps)
    P(T=3) intersection die rolled twice / P die rolled twice

    i mean how do i find the intersection??
    That is what my question was addressing. You need to look at the possible scenarios.

    e.g if first roll is 3, then it's not rolled twice, so that's not part of the event.

    IF first roll is 2, then the second roll must be ?

    Etc.
    • Thread Starter
    Offline

    11
    ReputationRep:
    (Original post by ghostwalker)
    That is what my question was addressing. You need to look at the possible scenarios.

    e.g if first roll is 3, then it's not rolled twice, so that's not part of the event.

    IF first roll is 2, then the second roll must be ?

    Etc.
    ohhhh ok got it... here in the last question ... im just stuck on how to find the intersection between B and C
    Name:  4.PNG
Views: 24
Size:  13.9 KB
    • Study Helper
    Offline

    13
    (Original post by pondsteps)
    ohhhh ok got it... here in the last question ... im just stuck on how to find the intersection between B and C
    Given P(C' n B') = 0.3

    What's the complementary event, and you should be able to work out P(BnC) from that with the other information given.
    • Thread Starter
    Offline

    11
    ReputationRep:
    (Original post by ghostwalker)
    Given P(C' n B' = 0.3

    What's the complementary event, and you should be able to work out P(BnC) from that with the other information given.
    how does that help us find the intersection?? so we do P(B u C)' = P(B)' + P(C)' - P(BnC)'??? is that how it works or not.... i didnt know how to deal with the prime
    • Study Helper
    Offline

    13
    (Original post by pondsteps)
    how does that help us find the intersection?? so we do P(B u C)' = P(B)' + P(C)' - P(BnC)'??? is that how it works or not.... i didnt know how to deal with the prime
    (B' n C') = (B u C)'

    They are not complementary events, they are the same event.

    The complementary event is B u C

    And P(B u C) = 1-0.3 = 0.7

    Now do the same with that.
    • Thread Starter
    Offline

    11
    ReputationRep:
    (Original post by ghostwalker)
    (B' n C' = (B u C)'

    They are not complementary events, they are the same event.

    The complementary event is B u C

    And P(B u C) = 1-0.3 = 0.7

    Now do the same with that.
    what do u mean by complemntary events???? is the rule i write out correct or wrong???
    • Study Helper
    Offline

    13
    (Original post by pondsteps)
    what do u mean by complemntary events???? is the rule i write out correct or wrong???
    You should know what complementary events are - check your textbook.

    What you wrote is incorrect, even the notation.

    P(B u C)' should be P( (B u C)' )
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    What newspaper do you read/prefer?
    Useful resources

    Make your revision easier

    Maths

    Maths Forum posting guidelines

    Not sure where to post? Read the updated guidelines here

    Equations

    How to use LaTex

    Writing equations the easy way

    Student revising

    Study habits of A* students

    Top tips from students who have already aced their exams

    Study Planner

    Create your own Study Planner

    Never miss a deadline again

    Polling station sign

    Thinking about a maths degree?

    Chat with other maths applicants

    Can you help? Study help unanswered threads

    Groups associated with this forum:

    View associated groups
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.