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How did ye do maths p2 Q6-c

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  • 14-06-2006 1:23pm
    #1
    emma.oshea
    Closed Accounts Posts: 18 ✭


    hey guys can any1 tell me how you did this question...and how sure you are that u were right!
    thanks a mil


Comments

  • Options
    #2
    Raphael
    Closed Accounts Posts: 8,880 ✭✭✭Raphael


    Higher, yeah? I'll do it out for you as I did it


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    #3
    emma.oshea
    Closed Accounts Posts: 18 ✭emma.oshea


    ya higher!
    thanks


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    #4
    Raphael
    Closed Accounts Posts: 8,880 ✭✭✭Raphael


    No problem, I have a day off today and I'm bored.
    Solution5.jpg
    Need me to explain any parts of it?


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    #5
    emma.oshea
    Closed Accounts Posts: 18 ✭emma.oshea


    that was quick, thanks very much, u made it look so easy.
    im trying to do 7(aii) just trying to figure out if its right.


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    #6
    Raphael
    Closed Accounts Posts: 8,880 ✭✭✭Raphael


    Want me to do that out for you as well?

    And it's only easy because i figured it out in the exam, wasn't easy the first time =)


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    #7
    emma.oshea
    Closed Accounts Posts: 18 ✭emma.oshea


    Please ya i just cant get my head around it...i know what its asking but i just cant figure the damn thing out! yo uknow for 61 why do u have the 30/30? and then all 1/30


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    #8
    Raphael
    Closed Accounts Posts: 8,880 ✭✭✭Raphael


    Solution6.jpg

    Because it's asking you to find the probability they're all on the same date, right? So when you look at each student you have to work out the probability that they have the same date as the person before them.

    In the case of the first person, there's no one before him, so any date is the same as the guy before him. There's a probability of 1 that his birthday won't be different from anyone we've looked at so far

    After that though, all the birthdays have to be the same date. Hence the 1/30's

    Say, for instance, the first guys birthday was june 8th. then all the rest of them ahve to be june 8th as well. But if his had been June 16th, they'd all have to be june 16th.

    Am I making sense?


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    #9
    emma.oshea
    Closed Accounts Posts: 18 ✭emma.oshea


    Cheere that makes perfect sence. For 7ai, why is it 10 and not 9? becasue there are only a possibility of 1-9 coming up?


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    #10
    emma.oshea
    Closed Accounts Posts: 18 ✭emma.oshea


    oops just realised that 0 could also appear....


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    #11
    Raphael
    Closed Accounts Posts: 8,880 ✭✭✭Raphael


    emma.oshea wrote:
    oops just realised that 0 could also appear....
    Yup, that's why. =)


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    #12
    emma.oshea
    Closed Accounts Posts: 18 ✭emma.oshea


    thanks so much... i dont think i did very well but hey what can i do now!
    :)


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    #13
    Raphael
    Closed Accounts Posts: 8,880 ✭✭✭Raphael


    You never know, I'd say it's going to be marked fairly easily this year.


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    #14
    Glazun
    Registered Users Posts: 315 ✭✭Glazun


    You could form a terrorist organisation and kidnap the maths paper 2 answer books. :) Thats if you really wanted to. Though forming terrorist organisations is frowned upon..


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