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

Maths probability help

Announcements Posted on
Four hours left to win £100 of Amazon vouchers!! Don't miss out! Take our short survey to enter 24-10-2016
    • Thread Starter

    A bag contains 6 red disks, 4 blue disks and 5 green disks. A fair dice has 4 faces painted red and 2 other faces painted blue.
    Lisa takes a disk at random from the bag and records it's colour.m
    Lisa then throws the dice twice and each time records the colour of the face it lands on.
    Work out the probability that all three of the three colours Lisa records are red.

    Thank you! xxxx

    So you're working out the probability that the disk taken from the bag is red AND the face landed on the first dice is red AND the face landed on the second dice is red.
    OR --- repeat for the other colours to get the final probability.
    For and you multiply, add for OR.

    Let X be the number of red disks
    P(X=3) = 3C3 * (2/5)^3 * (3/5)^3-3
    P(X=3) = 2/5 * 2/5 * 2/5
    = 8/125

    Never mind, answered better by other posters.
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: July 4, 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 find
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.