Mathematics: Post your doubts here!

[reina81]

In O/N 2004 P6 Q1(ii) - I don't understand why we can't use (5P4/2!)*(5!/2!)
http://www.xtremepapers.com/papers/...AS Level/Mathematics (9709)/9709_w04_qp_6.pdf

 

[DragonCub]

In O/N 2004 P6 Q1(ii) - I don't understand why we can't use (5P4/2!)*(5!/2!)
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w04_qp_6.pdf

What does (5P4)/2! mean? I think it should be (4P4)/2! since there are one more consonant than vowel. The order should be
vow-con-vow-con-vow-con-vow-con-con.

 

[reina81]

What does (5P4)/2! mean? I think it should be (4P4)/2! since there are one more consonant than vowel. The order should be
vow-con-vow-con-vow-con-vow-con-con.

But it needs to start with a consonant and the vowel. they need to alternate. that's why i thought the order should have been C-V-C-V-C-V-C-V-C.

 

[DragonCub]

But it needs to start with a consonant and the vowel. they need to alternate. that's why i thought the order should have been C-V-C-V-C-V-C-V-C.

OOUCH I thought it starts with a vowel... So that's why I feel weird about this question. Sorry, I got the wrong way
The order should be C-V-C-V-C-V-C-V-C. So that is 5!/2! × 4!/2!

 

[redapple20]

A factory makes a large number of ropes with lengths either 3 m or 5 m. There are four times as many
ropes of length 3 m as there are ropes of length 5 m.
) One rope is chosen at random. Find the expectation and variance of its length

ummm.....is this AS stats ??[/quote]
we got this in our mock!

 

[redapple20]

A factory makes a large number of ropes with lengths either 3 m or 5 m. There are four times as many
ropes of length 3 m as there are ropes of length 5 m.
) One rope is chosen at random. Find the expectation and variance of its length

ummm.....is this AS stats ??[/quote]
yes

 

[redapple20]

aoa wr wb

i need help with this question too..

this is partial fractions then integretion then making subject of formula

 

[redapple20]

this is partial fractions then integretion then making subject of formula

wan me to solve it?

 

[XPFMember]

wan me to solve it?

nopes jazakAllah...

already solved by another member...i was actually making a small mistake..though was doing the correct method!

it's ok..thanks a lot..

 

[redapple20]

nopes jazakAllah...

already solved by another member...i was actually making a small mistake..though was doing the correct method!

it's ok..thanks a lot..

cool

 

[1357913579]

can some one check and tell me whether the questions i have solved as coorect or not?

Assalamoalikum
xpf member have you solved this question? i dont know why iam not able to do this

 

[redapple20]

cool

now solve this plx

prove the identity sin^2 (2x) (cosec^2 (x)-sec^2 (x))= 4cos2x​

 

[XPFMember]

now solve this plx

prove the identity sin^2 (2x) (cosec^2 (x)-sec^2 (x))= 4cos2x​

Here: sin^2 (2x) (cosec^2 (x)-sec^2 (x))= 4cos2x
Sin^2 (2x) è4sin^2x cos^2 x
cosec^2 (x)-sec^2 (x) è 1/sin^2 x – 1/ cos^2 x = (cos^2 x – sin^2 x ) / (sin^2 x cos^2 X)
cos^2x – sin^2 x = cos 2x

now just simplify...
P.S. kinda difficult to put each and every step...that’s why did this way..

 

[Esme]

ummm.....is this AS stats ??

we got this in our mock![/quote]

The probability of 3cm is 4/5 and of 5cm is 1/5. Hence Expecance will be (3 x 4/5)+(5 x 1/5). similarly variance will be deduced using the formula Var(X)= E(X^2)-E(X)^2. Do you know the ans ??

 

[leadingguy]

well m unable to find m.s of may june 2002 paper 3 in the past papers coloumn or might b possible m missing that so plz can any one post me the link???? here?

 

[Jaf]

In O/N 2004 P6 Q1(ii) - I don't understand why we can't use (5P4/2!)*(5!/2!)
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w04_qp_6.pdf

Why 5P4? There are 4 vowels (with one repetition) and 5 consonants (with 1 repetition) and you are to use all of them in your arrangements.

 

[slayer]

Hello guys, how do I use the equation of an area (1/2 ab sin a) to find the angle when I dont have any angles and my to sides are 14 and 10

 

[sea_princess]

Assalamoalikum,
here you go
soory iam not sure about the order

thanx a lot but how did you know that u must convert t to radians not keep as degrees in the second part?

 

[sea_princess]

ummmmm......yea thank you but this is jus the basics. The questions in the tutorial are easy to solve n understand. However, i go totally blank wen i see questions like this :
View attachment 7510
If possible plz explain the iii) iv) n v) bit .

Here's the mark scheme: http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w10_ms_61.pdf

iii) u have 6 different colours out of which you'll choose 4 ,also the order in which you put the pegs matters so the answer is 6P4
, but I need explanation for the other two

 

[sea_princess]

This is so hard i cant understnd a thing...... can any 1 explain me this im in need of serious help!!!!!

View attachment 7397

Please help me solve this question .....
THIS IS 2011 OCT/NOVEMBER
STATISTICS PAPER 62

question 5:
i- assume that the probability that the spinner lands on the blue side is x
that will make P( landing on red)= 4x , P(landing on green)= 3x , the probability can never exceed 1
so now you have x+4x+3x = 1
8x=1 >>>>> x= 1/8 ( this is the probability it lands on the blue side)
ii- the spinner lands on a different colour each time , so that makes the possible arrangements of colours ( RGB, RBG, BRG, BGR, GRB, GBR) so now the probability is ( 1/8 X 4/8 X 3/8) X 6 = 9/64 ( this is because you'll only put the probabilities in different order while multiplying them for 6 times ,so as a shortcut you multiply them once and multiply the result by 6)
iii- from (i) the probability of landing on blue is 1/8 , so ( 1-p)= 7/8, and the n is given in the question to be 136
so first get the mean = np= 136 X 1/8 =17 , variance = np(1-p)= 136 X 1/8 X 7/8 =14.875
now P (it will land on blue less than 20 times )= P( Z < (19.5 - 17 )/ square root 14.875)= P ( Z < 0.648) , get it from the normal distribution table, it will equal 0.7415 = 0.742

I'll do the rest later