Results are out! Find what you need...fast. Get quick advice or join the chat
x

Unlock these great extras with your FREE membership

  • One-on-one advice about results day and Clearing
  • Free access to our personal statement wizard
  • Customise TSR to suit how you want to use it

Sets

Announcements Posted on
Rate your uni — help us build a league table based on real student views 19-08-2015
  1. Offline

    ReputationRep:
    (Counting words). How many 4-letter words do not begin
    or end with a vowel?
    [Here the alphabet is assumed to be {a, b, c, . . . , z} and the set of vowels is
    {a, e, i, o, u}. A (mathematical) word is any string of letters: it need not be
    a word in any language.]
    rep for good help
  2. Offline

    ReputationRep:
    surely you could say there are 21 different possibilities for the 1st and 4th letters, and 26 different possibilities for the 2nd and 3rd letters.. so there are 21*21*26*26 possibilities?

    not sure if thats correct just a quick idea
  3. Offline

    ReputationRep:
    (Original post by just george)
    surely you could say there are 21 different possibilities for the 1st and 4th letters, and 26 different possibilities for the 2nd and 3rd letters.. so there are 21*21*26*26 possibilities?

    not sure if thats correct just a quick idea
    ok how sure are you?
  4. Offline

    ReputationRep:
    well between 0 and 9 inclusive there are 10 digits.. and there are 100 2 digit numbers if you include 00, so in that case there are 10 possible 1st digits and 10 possible 2nd digits giving 10*10 possible 2 digit numbers.. there are also 10*10*10 3 digit numbers and 10*10*10*10 4 digit numbers. so by the same logic my thing works, providing there is no problem with repeating letters (e.g. BBBB is a word?) etc..

    short version.. pretty sure
  5. Offline

    ReputationRep:
    (Original post by just george)
    well between 0 and 9 inclusive there are 10 digits.. and there are 100 2 digit numbers if you include 00, so in that case there are 10 possible 1st digits and 10 possible 2nd digits giving 10*10 possible 2 digit numbers.. there are also 10*10*10 3 digit numbers and 10*10*10*10 4 digit numbers. so by the same logic my thing works, providing there is no problem with repeating letters (e.g. BBBB is a word?) etc..

    short version.. pretty sure
    ok cheers!

Reply

Submit reply

Register

Thanks for posting! You just need to create an account in order to submit the post
  1. this can't be left blank
    that username has been taken, please choose another Forgotten your password?
  2. this can't be left blank
    this email is already registered. Forgotten your password?
  3. this can't be left blank

    6 characters or longer with both numbers and letters is safer

  4. this can't be left empty
    your full birthday is required
  1. By joining you agree to our Ts and Cs, privacy policy and site rules

  2. Slide to join now Processing…

Updated: February 29, 2012
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

New on TSR

Rate your uni

Help build a new league table

Poll
How do you read?
Study resources
Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.