Results 1 to 17 of 17

Thread: simple probability question

  1. #1
    Executive Member bleakarcher's Avatar
    Join Date
    Jul 2011
    HSC
    2013
    Gender
    Male
    Posts
    1,481
    Rep Power
    2

    simple probability question

    In Tasmania, a car license consists of two letters followed by four digits. Find how many of these are possible if the second letter is X and the third digit is 3.

    Thanks

  2. #2
    Cadet
    Join Date
    Jun 2012
    HSC
    2012
    Gender
    Male
    Posts
    55
    Rep Power
    1

    Re: simple probability question

    we havent done probability in our school and i have no idea of the method but ill give it a go!

    for letters its 26....then for numbers there are three digits that can change so 9 in each...so 26 x 9 x 9= 2106

    NOTE- this is complete guess and i would recommend to check it with an experienced person...

    EDIT- its 10 for each not 9....so 26 x 10 x 10= 2600

  3. #3
    Executive Member bleakarcher's Avatar
    Join Date
    Jul 2011
    HSC
    2013
    Gender
    Male
    Posts
    1,481
    Rep Power
    2

    Re: simple probability question

    yeh I got 2600 but answers at the back of the cambridge textbook say 26000...

  4. #4
    Member zeebobDD's Avatar
    Join Date
    Oct 2011
    HSC
    2012
    Gender
    Male
    Posts
    401
    Rep Power
    2

    Re: simple probability question

    two letters and four digits so first like theres 25 possible ways second one is already chosen
    first digit theres 9 second 8 third already chosen and fourth 7

    so 25*9*8*7 = 12600

    i assume the digits are 0-9 LOL at me :L

    wait you didnt mention if they repeat or not?

  5. #5
    Cadet
    Join Date
    Jun 2012
    HSC
    2012
    Gender
    Male
    Posts
    55
    Rep Power
    1

    Re: simple probability question

    Quote Originally Posted by bleakarcher View Post
    yeh I got 2600 but answers at the back of the cambridge textbook say 26000...
    i am total idiot...its 26..and 10 each for three digits...so 26 x 10 x 10 x 10= 26000 there u go

  6. #6
    Member EpikHigh's Avatar
    Join Date
    Dec 2011
    HSC
    2013
    Gender
    Male
    Posts
    323
    Rep Power
    2

    Re: simple probability question

    Quote Originally Posted by bleakarcher View Post
    In Tasmania, a car license consists of two letters followed by four digits. Find how many of these are possible if the second letter is X and the third digit is 3.

    Thanks
    Alright so first of all there has to be two letter and the second letter has to be X so its 26 x 1 right? which is just 26, then there are only 3 digits that can be used in the licence plate so 26 x 10^3 = 26000.

    God, I love perms and combs.
    ​ HSC 2013'

    | Mathematics Extension 1 | Mathematics 2U | English Advanced | Physics | Chemistry| Economics

    Goals -

    -ATAR Goal 98+, Actuarial Studies @ UNSW
    - MBBS @ UNSW? Maybeh?


  7. #7
    Member Peeik's Avatar
    Join Date
    Mar 2009
    HSC
    2009
    Gender
    Male
    Location
    Sydney
    Posts
    271
    Rep Power
    4

    Re: simple probability question

    Wouldnt the solution just be 26 * 10*10*10 = 26000?
    Bachelor of Education (Secondary:Mathematics)/Bachelor of Science @ USYD

  8. #8
    Moderator Carrotsticks's Avatar
    Join Date
    Jun 2009
    HSC
    N/A
    Gender
    Undisclosed
    Posts
    6,298
    Rep Power
    7

    Re: simple probability question

    Quote Originally Posted by bleakarcher View Post
    In Tasmania, a car license consists of two letters followed by four digits. Find how many of these are possible if the second letter is X and the third digit is 3.

    Thanks
    LX DD3D

    L = Letter
    D = Digit.

    First Letter has 26 options.

    First Digit has 10 options.

    Second Digit has 10 options.

    Last Digit has 10 options.

    26 x 10 x 10 x 10 = 26000
    Bachelor of Science (Adv. Mathematics) - University of Sydney:

  9. #9
    Member zeebobDD's Avatar
    Join Date
    Oct 2011
    HSC
    2012
    Gender
    Male
    Posts
    401
    Rep Power
    2

    Re: simple probability question

    you should include "repetition allowed in your question next time"

  10. #10
    Sequential Timske's Avatar
    Join Date
    Nov 2011
    HSC
    2012
    Uni Grad
    2016
    Gender
    Male
    Posts
    796
    Rep Power
    2

    Re: simple probability question

    Quote Originally Posted by bleakarcher View Post
    yeh I got 2600 but answers at the back of the cambridge textbook say 26000...
    It is 26000, Letters in alphabet is 26, and there are 10 digits. a car license consists of two letters followed by four digits

    Find how many of these are possible if the second letter is X and the third digit is 3. Since one letter and a digit is chosen we are left with

    26 * 10 * 10 * 10 = 26000
    B ECO@USYD 2013

  11. #11
    Executive Member bleakarcher's Avatar
    Join Date
    Jul 2011
    HSC
    2013
    Gender
    Male
    Posts
    1,481
    Rep Power
    2

    Re: simple probability question

    Isn't the third digit fixed though?

  12. #12
    Member EpikHigh's Avatar
    Join Date
    Dec 2011
    HSC
    2013
    Gender
    Male
    Posts
    323
    Rep Power
    2

    Re: simple probability question

    Quote Originally Posted by zeebobDD View Post
    you should include "repetition allowed in your question next time"
    Usually the question will state if there IS NOT repetition. If there is nothing stated you usually would just assume it's allowed because it doesn't say it isn't.
    ​ HSC 2013'

    | Mathematics Extension 1 | Mathematics 2U | English Advanced | Physics | Chemistry| Economics

    Goals -

    -ATAR Goal 98+, Actuarial Studies @ UNSW
    - MBBS @ UNSW? Maybeh?


  13. #13
    Executive Member bleakarcher's Avatar
    Join Date
    Jul 2011
    HSC
    2013
    Gender
    Male
    Posts
    1,481
    Rep Power
    2

    Re: simple probability question

    Quote Originally Posted by Timske View Post
    It is 26000, Letters in alphabet is 26, and there are 10 digits. a car license consists of two letters followed by four digits

    Find how many of these are possible if the second letter is X and the third digit is 3. Since one letter and a digit is chosen we are left with

    26 * 10 * 10 * 10 = 26000
    OMGGGGGGZZZZZZZZZZZZZZZZZZZZZZZZ

    My mind told me that there were 3 digits for some reason..

    Alright thanks guys.

  14. #14
    Sequential Timske's Avatar
    Join Date
    Nov 2011
    HSC
    2012
    Uni Grad
    2016
    Gender
    Male
    Posts
    796
    Rep Power
    2

    Re: simple probability question

    Quote Originally Posted by bleakarcher View Post
    Isn't the third digit fixed though?
    yeah but theres 4 digits, so thers 3 digits left
    B ECO@USYD 2013

  15. #15
    Member EpikHigh's Avatar
    Join Date
    Dec 2011
    HSC
    2013
    Gender
    Male
    Posts
    323
    Rep Power
    2

    Re: simple probability question

    Quote Originally Posted by bleakarcher View Post
    Isn't the third digit fixed though?
    It's a 4 digit number plate, the last number has to be 3, so that's 1 possible combination followed by 10^3
    ​ HSC 2013'

    | Mathematics Extension 1 | Mathematics 2U | English Advanced | Physics | Chemistry| Economics

    Goals -

    -ATAR Goal 98+, Actuarial Studies @ UNSW
    - MBBS @ UNSW? Maybeh?


  16. #16
    Senior Member Nooblet94's Avatar
    Join Date
    Feb 2011
    HSC
    2012
    Gender
    Male
    Posts
    942
    Rep Power
    2

    Re: simple probability question

    Quote Originally Posted by bleakarcher View Post
    OMGGGGGGZZZZZZZZZZZZZZZZZZZZZZZZ

    My mind told me that there were 3 digits for some reason..

    Alright thanks guys.

    I make mistakes like that all the time!
    SELLING high quality MATHS and PHYSICS notes


    Quote Originally Posted by nerdasdasd View Post
    Fukking mum took the iPad cause she caught me using it last night...... Gonna take retribution by clearing 500 from her bank if she doesn't comply (no more mr nice guy )

  17. #17
    Junior Member Frostbitten's Avatar
    Join Date
    May 2012
    HSC
    2013
    Gender
    Male
    Posts
    227
    Rep Power
    1

    Re: simple probability question

    If there were no restrictions, it would be 26 x 26 x 10 x 10 x 10 x 10
    But one letter slot is taken up and one number slot is taken up, so you ignore them.
    It now becomes 26 x 10 x 10 x 10 = 26000
    Or in the permutation format (nPr) which you would use the calculator for: 26P1 x 10P1 x 10P1 x 10P1 = 26000
    n = number of objects available
    r = the amount needed to be chosen

    Pretty much what everyone has said before XD

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •