Edexcel S1 A Level Maths

A few questions:

1) Are we given the formula for expectance? I always get it wrong.

2) How do you calculate s.d.? I think my teacher said, "The square of the means minus the mean of the squares", but I can't remember. This might be variance.

3) Does var^2 = s.d. or s.d.^2 = var?

1) E(X) = p times x
2) standard deviation is square root of variance; or simply put its square root x^2/n - (mean)^2
3) var^2 = s.d.

Reply 661

Hamushte

2

Original post by nukethemaly

Yeah I need help with this too!

Thank god it's not only me. :colondollar:

Reply 662

nukethemaly

11

Original post by Hamushte

Thank god it's not only me. :colondollar:

This might maybeeee help a bit: http://www.ltcconline.net/greenl/courses/201/regression/scatter.htm

Reply 663

Tplox

2

to draw a regression line
y=a + bx

so basically you get the mean of y and mean x

the regression line goes through the point of the co-ordinate (mean x,mean y)

also sub in y=0 to find x
and also x=0 to find y

so thoese 3 different point, with a ruler should allow you to draw a line

does that make sense??

Reply 664

Tplox

2

Original post by Hamushte

Can anyone talk me through how you go about plotting a line of regression?

didnt quote you, but answers it on another post

Reply 665

Tplox

2

Original post by rachaelGodchild

loool

.....what idea? you think? oh ight good for u!...btwn if you did chexk can u pls help me wit q5 june 6

yh sure

http://www.thestudentroom.co.uk/showthread.php?t=1619124&x=-375&y=-474
look for the pdf for

june 06

that might be able to help

also for 2b
http://www.examsolutions.net/maths-revision/statistics/normal-distribution/calc-mu-sigma/example-1.php

if the link doesnt work just refresh it a couple of times haha

ps, your idea, i guess i mean you 'dream' haha
if it is true then the test is gonna be easy lol

Reply 666

Xx4L3x

5

Original post by nukethemaly

Also for discrete uniform variance: E(X) = n + 1 / 2. and Var (X) = (n+1)(n-1)/12, n is your last term.

does this work with n being the number of terms?

Reply 667

rachaelGodchild

Original post by Tplox

yh sure

http://www.thestudentroom.co.uk/showthread.php?t=1619124&x=-375&y=-474
look for the pdf for

june 06

that might be able to help

also for 2b
http://www.examsolutions.net/maths-revision/statistics/normal-distribution/calc-mu-sigma/example-1.php

if the link doesnt work just refresh it a couple of times haha

ps, your idea, i guess i mean you 'dream' haha
if it is true then the test is gonna be easy lol

awww thanks!..but I tot examsolutions doesn't have video solution for dat particular quest

Reply 668

Hamushte

2

Original post by Tplox

to draw a regression line
y=a + bx

so basically you get the mean of y and mean x

the regression line goes through the point of the co-ordinate (mean x,mean y)

also sub in y=0 to find x
and also x=0 to find y

so thoese 3 different point, with a ruler should allow you to draw a line

does that make sense??

So if it was y = 1.2 +1.45x, for example, how would I go about doing it?

Reply 669

nukethemaly

11

Original post by Xx4L3x

does this work with n being the number of terms?

I guess it does yeah

Reply 670

nukethemaly

11

Original post by Tplox

to draw a regression line
y=a + bx

so basically you get the mean of y and mean x

the regression line goes through the point of the co-ordinate (mean x,mean y)

also sub in y=0 to find x
and also x=0 to find y

so thoese 3 different point, with a ruler should allow you to draw a line

does that make sense??

Thank youuuu!

Reply 671

Revisionbug

1

I missed q11 in c1 losing 11 mrks plus anothr dumb 5/6mrks i jst threw away like an idiot i found m1 hard and now im strugglin s1 im much more of a pure/core guy my a/a* is looking bleak im guna strugle to hit 480ums if i dnt smash this sigh.... :frown:

(

Reply 672

Tplox

2

Original post by Hamushte

So if it was y = 1.2 +1.45x, for example, how would I go about doing it?

so first find the mean for Y and the mean for X
that would given in the table and information data etc..

so plot that point

then do Y=0, therfore x is waterver it is thats your 2nd coordiante

and then to check do one for when x=o, then you get the value for y your 3rd coordinate

get a ruler, draw a line through those points