Turn on thread page Beta
    • Thread Starter

    The question is, the three events E1, E2, and E3 are defined in the same sample space. The events E1 and E3 are mutually exclusive. The events E1 and E3 are independent.

    Given that P(E1)= 2/5, P(E3)= 1/3 AND P(E1 U E2)= 5/8, FIND

    (a) P(E1 U E3)

    (b) P(E2)

    i have figured out the answer to (a) but not (b)

    Hey there, I think there is an error in the wording of the question. If P(E1) and P(E3) are both non-zero, it's not possible for E1 and E3 to be both mutually exclusive and independent at the same time.

    Independence implies: P(E1 ∩ E3) = P(E1) x P(E3)

    Mutual exclusivity implies: P(E1 ∩ E3) = 0

    Therefore P(E1 ∩ E3) = P(E1) x P(E3) = 0, but this is not possible because the question states that P(E1)= 2/5, P(E3)= 1/3

    I think it would make more sense if the question was "The events E1 and E3 are mutually exclusive. The events E1 and E2 are independent."
The home of Results and Clearing


people online now


students helped last year

University open days

  1. London Metropolitan University
    Undergraduate Open Day Undergraduate
    Sat, 18 Aug '18
  2. Edge Hill University
    All Faculties Undergraduate
    Sat, 18 Aug '18
  3. Bournemouth University
    Clearing Open Day Undergraduate
    Sat, 18 Aug '18
A-level students - how do you feel about your results?
Useful resources

Make your revision easier


Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here


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

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

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