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

Normal distribution question? URGENT!!

Announcements Posted on
Take our short survey, £100 of Amazon vouchers to be won! 23-09-2016
    • Thread Starter
    Offline

    2
    ReputationRep:
    X-N (45, SIGMA)
    P(W<54)=0.75
    SO 54-45/SIGMA = 0.67
    I don't understand where the 0.67 has come from, it's not in any of the tables what happened to the 0.75, why is it 0.67
    This came up in a paper before but I didn't understand it :'(
    This question was from June 2007 Edexcel S1 Q2e
    Please help me someone, my exam is tomorrow!
    Thanks
    • Thread Starter
    Offline

    2
    ReputationRep:
    BUMP
    • Thread Starter
    Offline

    2
    ReputationRep:
    Sorry for the bumping but this is really urgent
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by Cinnamon_Twist)
    X-N (45, SIGMA)
    P(W<54)=0.75
    SO 54-45/SIGMA = 0.67
    I don't understand where the 0.67 has come from, it's not in any of the tables what happened to the 0.75, why is it 0.67
    This came up in a paper before but I didn't understand it :'(
    This question was from June 2007 Edexcel S1 Q2e
    Please help me someone, my exam is tomorrow!
    Thanks
    just so I can find it easily
    Offline

    3
    ReputationRep:
    P(W&lt;54)=0.75


    P(Z&lt;\frac{54-45}{\sigma})=0.75

    Reading \ backwards \ from \ the \ tables, \  P(Z&lt;0.67) \approx 0.75

    \therefore \ P(Z&lt;\frac{54-45}{\sigma}) \approx P(Z&lt;0.67) \ i.e. \ \frac{54-45}{\sigma} \approx 0.67
    Offline

    1
    ReputationRep:
    I think you may be over-complicating things. Doesn't the question just ask you to find \sigma? You've done most of the work already!
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by Implication)
    P(W&lt;54)=0.75


    P(Z&lt;\frac{54-45}{\sigma})=0.75

    Reading \ backwards \ from \ the \ tables, \  P(Z&lt;0.67) \approx 0.75

    \therefore \ P(Z&lt;\frac{54-45}{\sigma}) \approx P(Z&lt;0.67) \ i.e. \ \frac{54-45}{\sigma} \approx 0.67
    Thank you so so so so much! +rep

    (Original post by olipal)
    I think you may be over-complicating things. Doesn't the question just ask you to find \sigma? You've done most of the work already!
    yeah, I think I just panicked because the exam is tomorrow- thanks for the reassurance!
    +rep
    Offline

    0
    ReputationRep:
    umm.. >>>http://www.examsolutions.co.uk/a-lev...d-solution.php <<< check it! =) hope it would help.
    Offline

    2
    ReputationRep:
    (Original post by olipal)
    I think you may be over-complicating things. Doesn't the question just ask you to find \sigma? You've done most of the work already!
    Maths, Palmer Maths
 
 
 
Write a reply…

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

Updated: May 23, 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.

Poll
Who will be the next permanent England boss?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read here first

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
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.