IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Math => Topic started by: superduper2009 on April 23, 2010, 04:39:59 pm

Title: Maths help paper 1 & 6 :D normal distribution :D :D :D
Post by: superduper2009 on April 23, 2010, 04:39:59 pm
Can someone solve the following question for me please ->
MAY/June 09 q 3 for paper 1 i.e. pure maths 1.... with all the working...
Also can you please explain when to use continuity correction and when not to use it for normal distribution in statistics
Title: Re: Maths help paper 1 & 6 :D normal distribution :D :D :D
Post by: astarmathsandphysics on April 23, 2010, 05:28:40 pm
2 hours
Title: Re: Maths help paper 1 & 6 :D normal distribution :D :D :D
Post by: astarmathsandphysics on April 23, 2010, 07:07:44 pm
For what paper and board
Title: Re: Maths help paper 1 & 6 :D normal distribution :D :D :D
Post by: superduper2009 on April 23, 2010, 08:23:00 pm
paper 1 cie
thanks in advance
Title: Re: Maths help paper 1 & 6 :D normal distribution :D :D :D
Post by: astarmathsandphysics on April 23, 2010, 08:44:56 pm
a)(2+3x)^5 =5C0*2^5*(3x)^0+5C1*2^4*(3x)^1+5C2*2^3*(3x)^2=32+240x+720x^2
b)(1+ax)(2+3x)^5 =(1+ax)(32+240x+720x^2)=..+x^2(720+240a)+...
since the x^2 term is 0 720+240a=0 so a=-3

Title: Re: Maths help paper 1 & 6 :D normal distribution :D :D :D
Post by: astarmathsandphysics on April 23, 2010, 08:54:25 pm
Continuity corrections explained here

http://www.astarmathsandphysics.com/a_level_maths_notes/a_level_maths_notes_s2_menu.html
Title: Re: Maths help paper 1 & 6 :D normal distribution :D :D :D
Post by: superduper2009 on April 23, 2010, 09:03:56 pm
Thank you sooo much..
can you help me with one more thing...
in the same paper...can you please do question number 2 as well...
thanks in advance
+rep
Title: Re: Maths help paper 1 & 6 :D normal distribution :D :D :D
Post by: astarmathsandphysics on April 23, 2010, 09:09:37 pm
kx-4=x^2 -2x
x^2-(2+k)+4=0
2 distinct points so b^2 -4ac>0
(-(2+k))^2 -4*1*4>0
4+4k+k^2-16>0
k^2+4k-12>0
(k+6)(k-2)>0
k<-6 or k>2

see also
Title: Re: Maths help paper 1 & 6 :D normal distribution :D :D :D
Post by: superduper2009 on April 23, 2010, 09:19:27 pm
That was fast...
Thanks a lot :D
By the way ur amazing ... and thank you LOADS & LOADS for this amazing website and freeexampapers.com...... they helped me out ... ALOT ...and i really mean ALOT
Title: Re: Maths help paper 1 & 6 :D normal distribution :D :D :D
Post by: astarmathsandphysics on April 23, 2010, 09:22:25 pm
We try
Title: Re: Maths help paper 1 & 6 :D normal distribution :D :D :D
Post by: superduper2009 on April 23, 2010, 09:30:10 pm
one more quick question :P
cie october november 2008 paper 6..... question 1
I get the mean...but i get the standard deviation wrong...
can you please explain how to calculate the standard deviation

EDIT
STOP STOP... I GOT IT I WASN'T SQUARING THE MEAN SORRY SORRY  :D
Title: Re: Maths help paper 1 & 6 :D normal distribution :D :D :D
Post by: astarmathsandphysics on April 23, 2010, 09:34:24 pm
Use \sigma =sqrt{\frac {\sum x^2 -n { \bar x}^2}{n-1}}
where \bar x =\frac {\sum x}{n}
Title: Re: Maths help paper 1 & 6 :D normal distribution :D :D :D
Post by: superduper2009 on April 23, 2010, 09:36:54 pm
thank you sooooooooooooooooooooo much :D :D :D :D :D :D i really really appreciate it
Title: Re: Maths help paper 1 & 6 :D normal distribution :D :D :D
Post by: astarmathsandphysics on April 23, 2010, 09:40:06 pm
Done now. Every time I try something new with the version of latex on the forum I have to do some pfaffing around