Hey! Sign in to get help with your study questionsNew here? Join for free to post

Team game - pairing probability issue (non-academic problem)

Announcements Posted on
Would YOU be put off a uni with a high crime rate? First 50 to have their say get a £5 Amazon voucher! 27-10-2016
    • Thread Starter

    So I'm playing a two team game.There are 20 players initially and we know that the makeup of team A is 16 players and team B is 4 players.

    Assuming random selection), given each player is 'attached' to another player into pairs, in a way not related to the teams A or B, what is the probability of an A-A pair, a A-B pair and a B-B pair please?
    • Thread Starter

    P(A) = 4/5
    P(B) = 1/5
    N = 20

    P(A-A) = 4/5 * 4/5 = 1/5
    P(A-B) = 4/5 * 1/5 = 4/25
    P(B-B) = 1/5 * 1/5 = 1/25

    So that's the probability for the first draws, I think. Where do I go from here?

    edit: or is it different because there is now 1 less element in the set and so it's not the same probability multiplied by itself?

    edit 2: yeah, this looks wrong. Please help! xD
    • Thread Starter

    I'd very much appreciate even a methodology here if an answer is too tedious

    (Original post by BizzStrut)
    I'd very much appreciate even a methodology here if an answer is too tedious
    This is how I would approach the problem. After being selected a person is removed from the list of people that can be selected.
    Therefore the following probabilities occur for the first draw:
    P(AA)=\frac{16}{20}\times\frac{1  5}{19}=\frac{60}{95}
    P(AB)=2\times\frac{16}{20}\times  \frac{4}{19}=\frac{32}{95}
    P(BB)=\frac{4}{20}\times\frac{3}  {19}=\frac{3}{95}
    Note that there are two permuations for the AB pairing as it can be paired AB or as BA.
    Use this principle to now look at the question from a combination standpoint. Any further help needed just ask.

Write a reply…


Submit reply


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. Oops, you need to agree to our Ts&Cs to register
  2. Slide to join now Processing…

Updated: May 29, 2016
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.

Would you rather be able to
Useful resources

Make your revision easier


Maths Forum posting guidelines

Not sure where to post? Read here first


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
Study resources

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

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