Mathematics: Post your doubts here!

[angelicsuccubus]

bad idea! you need a fresh mind to do s1! Especially the latest papers. Requires a lot of thinking!

I do m2

 

[RGBM211]

cudnt do the probability one sorry im getting 2/49 as ans

it will be 2c1/7c1

 

[omar hazem]

when lets say, u are given...a fixed nmber of trial eg a dice is thrown 200 times.... use a suitable approximation to find the probability that more than 60 times it landed on a 3..... or when u hv all the binomial related data ie; number of trials....probability of success and failure...and u need to find the probability of a large event.......

u mean that they give to me a large fixed number of trials and i need to find the probability of a smaller number so we use in this case continuity correction ??

 

[tasnim007]

Is it just me or is M2 actually easier than P3?

 

[AdeelRox]

due can an of u plx help me with Q.5, p61 part (i)

 

[Esme]

box-and-whisker plots can be drawn eithr horizontally or vertically right ???
cuz in class i've done vertically but in the mark scheme its always horizontal.
any help is appreciated.

 

[shan5674]

You have s1 in the morning?

Nope i do s2 which is at 10am

 

[Mobeen]

in normal distribution if for example its given to find the probablity of X>35 and mean = 30 and variance = 1.5. sometimes it takes it as 35-30/1.5 and sometimes 35.5-30/1.5 .. why is that ??
the values are just random.

 

[umarFM]

u mean that they give to me a large fixed number of trials and i need to find the probability of a smaller number so we use in this case continuity correction ??

http://www.xtremepapers.com/papers/...S Level/Mathematics (9709)/9709_w11_qp_61.pdf
Q1 look at this question.... u hv fixed nmber of trial.... probability of success and failure....all the data fr binomial...u need to find the probability for more than 210....u jst cant add 0 to 210 ways.....an approximation is needed....hence u cnvrt frm binomial to normal.....

 

[AdeelRox]

guys can any of u plx help me with q.5 part (i)
paper 61

 

[hm12]

in normal distribution if for example its given to find the probablity of X>35 and mean = 30 and variance = 1.5. sometimes it takes it as 35-30/1.5 and sometimes 35.5-30/1.5 .. why is that ??
the values are just random.

thats continuity correction its being discussed all over the last few pages its always applied when you convert binomial into normal usually when its written in the question use suitable approximation then its applied

 

[omar hazem]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_61.pdf
Q1 look at this question.... u hv fixed nmber of trial.... probability of success and failure....all the data fr binomial...u need to find the probability for more than 210....u jst cant add 0 to 210 ways.....an approximation is needed....hence u cnvrt frm binomial to normal.....

ahaaaaaaaaaaaaaa thank u so much now i understood so we use the cc when u need to find the probability of a smaller number in relative to a larger fixed number am I right?

 

[hm12]

guys can any of u plx help me with q.5 part (i)
paper 61

you did not mention the year?

 

[AdeelRox]

2011

 

[AdeelRox]

november

 

[driggerbilal]

Assalamoalaikum!!

For permutations and combinations watch this whole series of the tutorial, and you're good to go! http://www.examsolutions.co.uk/maths-re ... rial-1.php


I see people finding permutations and combinations hard, but honestly i enjoy it a lot..

And one more thing, (you may understand this better may be after you've gone through the topic, but anyways)
to make out when you have to use permutation (nPr of the calculator) and when to use combinations (nCr) , checck if the different arrangements of the selections will make any difference or not...if it does then you've to use nPr, and if it doesn't then u must use nCr.

Eg. lets say I want to choose two numbers from a total of three..how many possible selections are there?

now see i may choose 1 2 ; 1 3 ; 2 3
now the no. i've chosen can be written as 2 1 ; 3 1 ; 3 2

and obviously, this is giving me different numbers, so here arrangement does matter..so go for nPr => 3P2 = 6

but say if i got to chose 2 people from a total of 3 (A, B and C)

so possibilities are A B ; A C ; B/ C
and if i make this as B A ; C A ; C B
it doesn't make any difference as in the end there are the same people whether A first or B first....so that means arrangement does not matter...we'll use nCr => 3C2 = 3

P.S. These were pretty simple examples, I used them to explain the concept...you'll find this part of my explanation helpful when later on you tackle some more harder situations...this part really makes this thing easy...it did for me

thnku buddy

 

[Esme]

box-and-whisker plots can be drawn eithr horizontally or vertically right ???
cuz in class i've done vertically but in the mark scheme its always horizontal.
any help is appreciated.

suggestions anybody ??

 

[hm12]

2011

may/june or oct/nov please write full detail only then anyone can help!

 

[AdeelRox]

may/june or oct/nov please write full detail only then anyone can help!

nov 2011 p61 q.5 part (i)

 

[hm12]

suggestions anybody ??

its better you draw it horizontally as done in the marking scheme because in class and in books i have always seen it horizontally