Results are out! Find what you need...fast. Get quick advice or join the chat
Hey there Sign in to join this conversationNew here? Join for free

S1 normal distribution question

Announcements Posted on
    • Thread Starter
    • 0 followers
    Offline

    ReputationRep:
    Hi, im struggling with this question

    when you look up 0.9300 in the normal dist. table, you have to choose between

    1.47- 0.9292
    1.48-0.9306

    do you pick P(z<1.48) cos its closer to 0.9300? if so, how did they get 1.476..i.e how do you precisely pick which one is more appropriate? :confused:
    Attached Thumbnails
    Click image for larger version. 

Name:	s1 question.jpg 
Views:	18 
Size:	26.9 KB 
ID:	142089  
    • Thread Starter
    • 0 followers
    Offline

    ReputationRep:
    bump?
    • 0 followers
    Offline

    ReputationRep:
    Same thing happened to us in class. Our teacher told us that should never happen in a real exam, that all of the answers would be accurate if we'd got them right, but for the purposes of those questions to either use the closest or make an estimate. Do you have the answer sheet to work out what they wanted?

    We were told it was because different people print different values, so if you use say an Edexcel worksheet with an independent ND table, you're likely not to find the results you need.
    • 7 followers
    Offline

    ReputationRep:
    This is probably an old paper. They used to do it by linear interpolation. It's in FP1 but it's fairly simple (I think). It's basically the "fraction of the way along" is the correct value. 0.93 is 0.008 above the lower value (which is 0.9292, corresponding to 1.47), out of a total 'gap' of 0.014. 0.008/0.014 = 0.6, to 1 decimal place. So 60% of the way between 1.47 and 1.48 is the correct value, i.e. 1.476.

    But don't worry, you don't have to do it!
    • Thread Starter
    • 0 followers
    Offline

    ReputationRep:
    (Original post by starkrush)
    This is probably an old paper. They used to do it by linear interpolation. It's in FP1 but it's fairly simple (I think). It's basically the "fraction of the way along" is the correct value. 0.93 is 0.008 above the lower value (which is 0.9292, corresponding to 1.47), out of a total 'gap' of 0.014. 0.008/0.014 = 0.6, to 1 decimal place. So 60% of the way between 1.47 and 1.48 is the correct value, i.e. 1.476.

    But don't worry, you don't have to do it!
    I know how to do linear interpolation :P I sat FP1 in Jan!

    Thanks for the help guys
    • 0 followers
    Offline

    ReputationRep:
    I'd pick the closest one...

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. By joining you agree to our Ts and Cs, privacy policy and site rules

  2. Slide to join now Processing…

Updated: April 15, 2012
New on TSR

Find out what year 11 is like

Going into year 11? Students who did it last year share what to expect.

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