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S1 June 2011 Edexcel - Model answers and common questions in the FIRST POST

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    Revision thread for the S1 Jan paper.

    This is taken from the June 11 thread but has all the attachments you will find useful. I will put back up the June paper and model answers in the wee k of the Jan exam. I have taken them down as they may be used for mock exams.

    I DO NOT HAVE ACCESS TO THE EXAMINATION PAPERS BEFORE THE EXAM, I ONLY HAVE ACCESS TO THEM ONCE THE PAPER IS COMPLETED

    I will be happy to remove any content I have uploaded if requested by site admin
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    Model Answers
    Attached Images
  1. File Type: pdf 09 Jan S1 Model.pdf (537.3 KB, 1691 views)
  2. File Type: pdf 08 Jan S1.pdf (198.2 KB, 1105 views)
  3. File Type: pdf 08 June S1 Model.pdf (236.5 KB, 980 views)
  4. File Type: pdf 07 June S1 Model.pdf (646.7 KB, 764 views)
  5. File Type: pdf 07 Jan S1 Model.pdf (341.2 KB, 700 views)
  6. File Type: pdf 09 June S1 Model Solutions red.pdf (882.8 KB, 1120 views)
  7. File Type: pdf 10 Jan Solutions.pdf (826.1 KB, 938 views)
  8. File Type: pdf 10 June S1.pdf (492.9 KB, 1420 views)
  9. File Type: pdf 11 Jan S1 Model red.pdf (590.2 KB, 2302 views)
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    thanks for the revision notes, really useful
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    More Model answers


    Tip - An obvious one. Learn how to use your Stats mode on your calc to check your answers.
    Attached Images
  10. File Type: pdf 06 June S1 Model.pdf (582.4 KB, 1264 views)
  11. File Type: pdf 06 Jan S1 Model.pdf (322.5 KB, 569 views)
  12. File Type: pdf 05 June S1 Model.pdf (341.3 KB, 500 views)
  13. File Type: pdf 05 Jan S1 Model.pdf (330.7 KB, 473 views)
  14. File Type: pdf 04 Nov S1 Model.pdf (321.5 KB, 406 views)
  15. File Type: pdf 04 Jan S1 Model.pdf (333.2 KB, 418 views)
  16. File Type: pdf 04 June S1 Model.pdf (324.5 KB, 439 views)
  17. File Type: pdf 03 June S1 Model.pdf (570.2 KB, 387 views)
  18. File Type: pdf 03 Nov S1 Model.pdf (525.5 KB, 428 views)
  19. File Type: pdf 03 Jan S1 Model.pdf (578.5 KB, 572 views)
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    (Original post by Arsey)
    Tip - An obvious one. Learn how to use your Stats mode on your calc to check your answers.
    I've never actually used that before. What sort of stuff can that mode do?
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    More model answers


    It can work out measures of location and dispersion.

    If you enter the data for a frequency table, it will calculate all the sums (x, x^2); it will also calculate the mean and standard deviation (but not median or quartiles etc).

    You can enter a bivariate table and it will calculate all of the sums (x, X^2, y, y^2, xy); it will calculate PMCC and the values of a and b in the least squares regression line.

    The Casio 991ES can also do some normal distribution calculations.
    Attached Images
  20. File Type: pdf 02 Nov S1 Model.pdf (339.3 KB, 507 views)
  21. File Type: pdf 02 June S1 Model.pdf (660.4 KB, 415 views)
  22. File Type: pdf 02 Jan S1 Model.pdf (717.6 KB, 378 views)
  23. File Type: pdf 01 June S1 Model.pdf (313.2 KB, 401 views)
  24. File Type: pdf 01 Jan S1 Model.pdf (663.8 KB, 457 views)
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    Arsey, cheers bro
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    (Original post by Arsey)
    It can work out measures of location and dispersion.

    If you enter the data for a frequency table, it will calculate all the sums (x, x^2); it will also calculate the mean and standard deviation (but not median or quartiles etc).

    You can enter a bivariate table and it will calculate all of the sums (x, X^2, y, y^2, xy); it will calculate PMCC and the values of a and b in the least squares regression line.

    The Casio 991ES can also do some normal distribution calculations.
    Hi arsey,

    if i click stat mode i get a load of options.

    If, for instance, i choose option (2) = a+bx then is this the regression line mode? when i click it i just get a table of x with a table of y next to it. How do i get it to be of use.

    thanks again
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    (Original post by Arsey)
    Model Answers
    I see on the Jan 2011 paper, you've written:

     \frac{1}{2}n = 16 then time, continuous.

    If it weren't continuous, what would you have done differently?
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    you are quite unlikely to see a discrete grouped data question. However, if the data were discrete the values in the tables would be the boundary points, not, as in this case, the midpoint between the classes.

    So, if the data were discrete the median would be 0.5 higher.
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    (Original post by Extricated)
    Hi arsey,

    if i click stat mode i get a load of options.

    If, for instance, i choose option (2) = a+bx then is this the regression line mode? when i click it i just get a table of x with a table of y next to it. How do i get it to be of use.

    thanks again
    Activate state mode for a list of options on your calculator (doing this from memory, so please excuse any minor mistakes)

    The list of options contain things such as 1-Var (the variance setting) and A+Bx (regression line)

    Selecting the 1-Var setting gives you a table with X values - input them and then press AC. Then press Shift-1 to enter stat functions using your previously tabulated information.

    Shift-1 gives you a few options, and heres what they do -

    Type-change type of date
    Data-edit table
    Sum-Sigma X squared and Sigma X
    Var - Have a guess.

    If you had chosen the regression setting in the orignial list, you would get two tables X values and Y values, because it is regression, and then if you had chosen Shift-1, you would get the following options

    Type-Same as before
    Data-Same as before
    Sum-All your Sigma Xs and Ys
    Var - All your Var, means and Standard Deviation stuff
    Reg - Regression stuff, you want option 3, the 'r' value
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    (Original post by H94)
    Activate state mode for a list of options on your calculator (doing this from memory, so please excuse any minor mistakes)

    The list of options contain things such as 1-Var (the variance setting) and A+Bx (regression line)

    Selecting the 1-Var setting gives you a table with X values - input them and then press AC. Then press Shift-1 to enter stat functions using your previously tabulated information.

    Shift-1 gives you a few options, and heres what they do -

    Type-change type of date
    Data-edit table
    Sum-Sigma X squared and Sigma X
    Var - Have a guess.

    If you had chosen the regression setting in the orignial list, you would get two tables X values and Y values, because it is regression, and then if you had chosen Shift-1, you would get the following options

    Type-Same as before
    Data-Same as before
    Sum-All your Sigma Xs and Ys
    Var - All your Var, means and Standard Deviation stuff
    Reg - Regression stuff, you want option 3, the 'r' value
    You are a legend, thanks! I don't get the last point though (probably because i'm thick), what do you mean by the 'r' value...i see it on the calculator but for regression don't you just need a and b? what does r tell u?

    also can your calculator also find variance from grouped data
    thanks
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    (Original post by extricated)
    you are a legend, thanks! I don't get the last point though (probably because i'm thick), what do you mean by the 'r' value...i see it on the calculator but for regression don't you just need a and b? What does r tell u?

    Also can your calculator also find variance from grouped data
    thanks
    nt probably...ur are thick! Rip shu
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    (Original post by Extricated)
    You are a legend, thanks! I don't get the last point though (probably because i'm thick), what do you mean by the 'r' value...i see it on the calculator but for regression don't you just need a and b? what does r tell u?

    also can your calculator also find variance from grouped data
    thanks
    most scientific calcs can find standard deviation in the stats mode, square that to give variance.

    on the casio calcs you need to turn on freq

    mode - down arrow - stats - frequency on

    shift 1 - stats mode - data

    when you put the data in you must use the mid-points as the first column of data and then the freq in the second column.

    the only thing it will not do is interpolate to find the median.
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    Question:
    The random variable X ~ N(mean, sigma^2)
    The lower quartile of X is 25 and the upper quartile of X is 45.
    Find the value of mean , and the value of sigma

    I dont understand how one would do this question systematically?
    thanks!
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    (Original post by pHneutral)
    Question:
    The random variable X ~ N(mean, sigma^2)
    The lower quartile of X is 25 and the upper quartile of X is 45.
    Find the value of mean , and the value of sigma

    I dont understand how one would do this question systematically?
    thanks!
    Think about it, the lower quartile is a point below which there is 25% of data
    Upper quartile is a point below which 75% data is.

    We're told X ~ N (mu, sigma^2)

    Forming equations now

    P(Z<(25-mu)/sigma) = 0.25 equation 1 (25% of data is less than lower quartile)
    P(Z<(45-mu)/sigma) = 0.75 equation 2 (75% of data is less than upper quartile)

    What you'd do next is form two simultaneous equations, eliminate mu or sigma, solve for one and substitute to find the other.
    Be careful with signs and phi value from tables when forming the two equations

    Can't really do the rest as i don't have tables with me atm

    That should help, though i have a feeling it might be wrong since i haven't touched stats for a few weeks now.
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    (Original post by Extricated)
    You are a legend, thanks! I don't get the last point though (probably because i'm thick), what do you mean by the 'r' value...i see it on the calculator but for regression don't you just need a and b? what does r tell u?

    also can your calculator also find variance from grouped data
    thanks
    r tells you the PMMC correlation co-efficient - dont just copy this and write it down since you could lose marks for accuracy and no working etc.

    It's a useful check to use your calculator at the end to check your answers.


    For grouped data like arsey said just plug in midpoints.
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    I dont know if i'll want to check, if I realise i failed it'll kill the rest of my holiday.
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    (Original post by No.1 Loner)
    I dont know if i'll want to check, if I realise i failed it'll kill the rest of my holiday.
    Yes, however, think how happy you'll be if you check Arsey's solutions and you've not made a single mistake (that you can remember)?

    What a dilemma.
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    (Original post by Arsey)
    Tip - An obvious one. Learn how to use your Stats mode on your calc to check your answers.
    Just wanted to ask with the past papers, when a given that approach is required with probability questions, the question says "given that..." however, looking at soloman papers, sometimes they don't write given that and make it quite ambiguous.

    Was wondering whether in the exam in 2 weeks whether they would actually say "given that" or could they make it unclear?

    Thanks!
 
 
 
Updated: January 17, 2013
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