Find the page no?

This question comes in this year nac test
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A person was given a task to calculate sum of all the page no's of a novel , but by mistake he added one page no twice ,therefore at the end he got sum 1000 ,now you have to find that page no which was added twice by him.

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  • CIVILPRINCESS
    CIVILPRINCESS

    @civilprincess-308hDv • Nov 11, 2010

    the answer is twenty... 😁

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  • Manish Goyal
    Manish Goyal

    @manish-r2Hoep • Nov 11, 2010

    i dont know answer but according to me also answer is 20

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  • CIVILPRINCESS
    CIVILPRINCESS

    @civilprincess-308hDv • Nov 11, 2010

    yeah i'm sure the answer is 20 anyone other answers:?:

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  • Leo
    Leo

    @leo-ZJQlmh • Nov 11, 2010

    How come twenty

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  • CIVILPRINCESS
    CIVILPRINCESS

    @civilprincess-308hDv • Nov 11, 2010

    i'm sorry i'm sorry the answer is 10. i made an arithmetic mistake. 😳 solution coming up

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  • Morningdot Hablu
    Morningdot Hablu

    @morningdot-6Xuj4M • Nov 11, 2010

    According to me the answer is 11.
    .
    the page number starts from 0.
    so the first term is 0.comman diff is 1.
    so the right sum of the total page is (n(n-1))/2;
    let he wrongly added the rth page so the rth page is (r-1){because zero comes first}.
    .
    now the final equation is like this {(n(n-1))/2}+{r-1}=1000.
    now n(n-1)+2(r-1)=2000.
    put n(n-1)=45*44;
    so 2(r-1)=20;
    r=11.

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  • CIVILPRINCESS
    CIVILPRINCESS

    @civilprincess-308hDv • Nov 11, 2010

    But we number the books with page numbers from 1 only right :?:

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  • CIVILPRINCESS
    CIVILPRINCESS

    @civilprincess-308hDv • Nov 11, 2010

    my solution is:

    sum of 'n' page numbers starting from one is given by n(n+1)/2.
    so n(n+1)/2<1000
    n(n+1)<2000.
    for n=44 we get the maximum value below 2000 ( which is 1980)
    so the sum will be 44*45/2=990.
    so 10 has been added twice

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  • Morningdot Hablu
    Morningdot Hablu

    @morningdot-6Xuj4M • Nov 11, 2010

    Oh shit.
    But the process is right.

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  • Morningdot Hablu
    Morningdot Hablu

    @morningdot-6Xuj4M • Nov 11, 2010

    Yes by my process also the answer is 10.
    final equation is like this (n(n+1))+2r=1000.
    put n(n+1)=44*45.
    2r=20 so the answer is 10.

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  • CIVILPRINCESS
    CIVILPRINCESS

    @civilprincess-308hDv • Nov 11, 2010

    yeah the process is right.😀 so the answer is right or any other answers :?:

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  • Leo
    Leo

    @leo-ZJQlmh • Nov 11, 2010

    No other answers 10 is right answer.

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  • Chaitali Sumita
    Chaitali Sumita

    @chaitali-sumita-Bn5O8f • Nov 25, 2010

    10 is the answer..

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  • HirenBarbhaya
    HirenBarbhaya

    @hirenbarbhaya-04r651 • Nov 30, 2010

    Nice Explanation!!!

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  • sachinswetha
    sachinswetha

    @sachinswetha-Ko1jA4 • Jan 31, 2012

    the answer is 10.
    sol:sum of first 44 numbers is 990.then we add 10 we get 1000.

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