Turn on thread page Beta
    • Thread Starter
    Offline

    5
    ReputationRep:
    I have a question:
    The random variable T can take values 1, 2, 3,...) and has a geometric distribution. It is given that P(T= 1 or 2) = 0.4375. Find the value of P(T=1). the answer is 0.25. I don't know how to do the geometric distribution and I don't know how to work out the probability of success. Please can you help me. Thanks
    •  Official Rep
    Offline

    16
    ReputationRep:
     Official Rep
    Sorry you've not had any responses about this. Are you sure you've posted in the right place? Here's a link to our subject forum which should help get you more responses if you post there.


    Just quoting in Fox Corner so she can move the thread if needed :wizard:
    Spoiler:
    Show
    (Original post by Fox Corner)
    x
    Offline

    14
    ReputationRep:
    (Original post by Sibghy)
    I have a question:
    The random variable T can take values 1, 2, 3,...) and has a geometric distribution. It is given that P(T= 1 or 2) = 0.4375. Find the value of P(T=1). the answer is 0.25. I don't know how to do the geometric distribution and I don't know how to work out the probability of success. Please can you help me. Thanks
    Well then, first step would be to look up what the geometric distribution is. T having a geometric distribution means  P(T=t) = (1-p)^{t-1}p where p is the probability parameter (usually it is the probability of a Bernoulli trial, and the geometric distribution usually measures the probability of how many failures you have before your first success - read the Wiki page).

    The events are mutually exclusive. Therefore P(T=1 or 2) = P(T=1) + P(T=2).

    Using the distribution above, you get P(T=1 or 2) = p + (1-p)p = 0.4375. This will give you a quadratic you can solve for p (almost certainly one value is negative and the other is positive - so you know which value is the solution you care about).

    Since P(T=1) = p, once you've found p, you're done!
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: November 6, 2016
The home of Results and Clearing

2,827

people online now

1,567,000

students helped last year

University open days

  1. Sheffield Hallam University
    City Campus Undergraduate
    Tue, 21 Aug '18
  2. Bournemouth University
    Clearing Open Day Undergraduate
    Wed, 22 Aug '18
  3. University of Buckingham
    Postgraduate Open Evening Postgraduate
    Thu, 23 Aug '18
Poll
How are you feeling about GCSE results day?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

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