Mathematics: Post your doubts here!

[Alice123]

I assume you have used the following method.
3 : 111
4 : 112, 121, 211
5 : 113, 131, 311, 122, 212, 221
6 : 123, 132, 312, 213, 231, 321, 114, 141, 411, 222

You can make it shorter by using permutation.

3 : 3!/3! = 1
4 : 3!/2! = 3
5 : 3!/2! + 3!/2! = 6
6 : 3!/2! + 3!/2! + 3!/2! + 3!/3! = 10

This can be done by intuition alone. I just showed you the working to make you understand. Hope you got it!!

thanks again

 

[Alice123]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_61.pdf
no 3 thanks in advance

 

[syed1995]

In Case = P(C) = 0.7
Not In Case = P(C`) = 0.3
Finds It = P(F)
CF = 0.7*1
C`F = 0.3*0.2

This question is pretty simple .. Just draw a tree diagram to solve it easily.

The Pen was in his case given that he finds it means.

P(In Case Given He Finds It)= (It was in Case and he finds it) over [ (It was in case and he finds it) + (It was not in case but he still finds it) ]
P(in C given F)= (CF)/(C`F+CF)
= 0.7*1/(0.7*1)+(0.3*0.2)
=0.7/0.7+0.06
=0.7/0.76

 

[Alice123]

In Case = P(C) = 0.7
Not In Case = P(C`) = 0.3
Finds It = P(F)
CF = 0.7*1
C`F = 0.3*0.2

This question is pretty simple .. Just draw a tree diagram to solve it easily.

The Pen was in his case given that he finds it means.

P(In Case Given He Finds It)= (It was in Case and he finds it) over [ (It was in case and he finds it) + (It was not in case but he still finds it) ]
P(in C given F)= (CF)/(C`F+CF)
= 0.7*1/(0.7*1)+(0.3*0.2)
=0.7/0.7+0.06
=0.7/0.76

thanks!!! dats simple, i wrote dat by mistake.. i'm sorry. i cudnt solve qs 3

 

[Iffat]

what didnt u get in no.3?
i just did the whole thing.check it again and sry i forgot to put 2x in the superscript value

oh its ok i found the ans..thanx

 

[applepie1996]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s06_qp_3.pdf
could someone please solve question 9 (ii)
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s07_qp_3.pdf
question 2 (ii)
question 7 (ii)
could someone infinity times please do them

 

[syed1995]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_61.pdf
no 3 thanks in advance

This question is really simple.

You need to make a probability distribution table ..

−2, −1, 0, 1, 2, 3, 4, 5

Probability for 0 = 1/10

Probability for any other number = (9/10) / 7 = 9/70

Part 1 is just simple .. add the probabilities of -2,-1,0 and 1.. which is 3*9/70 + 1/10 .. which equals 17/35

Variance = E(X^2)-(EX)^2

Multiply the probability by X and X^2 and add them all to get both the above values.

EX comes as 54/35 and E(X^2) comes as 54/7

Variance = 54/7 - (54/35)^2 = 5.334 Ans

And the last part .. well just see the table and do calculations.. And you will also notice the answer is same as first part.. first part included -2,-1,0,1 .. while this part has -1,0,1,2 .. so a = 1

 

[NIM]

hey guys, does anyone knows how to convert non linear exponential graph into linear graph, only graph points are give, we have to find equation also??? Plz help, i'll b thankful to you... thnx in advance ..

 

[Jspake]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w10_qp_13.pdf
Please help me with no. 9 (b) (ii).. I really don't understand how it is solved in the marking scheme.
Thanks

 

[Iffat]

Help needed

2008 oct-nov p1:
q2

2009 may-jun p1:
q4(ii)

2009 oct-nov p12:
q9(iii)
q10(i)(c)

 

[Kumkum]

Help needed

2008 oct-nov p1:
q2

2009 may-jun p1:
q4(ii)

2009 oct-nov p12:
q9(iii)
q10(i)(c)

oct/nov 08
2. 1+sinx/cosx = cosx/1+sinx take common denominator
= [(1+sinx)^2 + (cos^2)x]/cosx(1+sinx)
= (1 + 2sinx + (sin^2)x + (cos^2)x)/cosx(1+sinx) here an identity needs to be used : (cos^2)x +(sin^2)x = 1, so (sin^2)x = 1 - (cos^2)x
= (1 + 2sinx + 1 - (cos^2)x + (cos^2)x )/ cosx(1+sinx) , the '(cos^2)x' cancels out
= 2 + 2sinx/cosx(1+sinx)
= [2(1 + sinx)]/cosx(1+sinx) , the '1+sinx' cancels out
= 2/cosx hence equal to right hand side
hope you understood

 

[Alice123]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w12_qp_61.pdf
Pls explain 5ii
https://www.xtremepapers.com/community/members/syed1995.17088/
https://www.xtremepapers.com/community/members/dug.23386/
thanks in advance

 

[syed1995]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_61.pdf
Pls explain 5ii
https://www.xtremepapers.com/community/members/syed1995.17088/
https://www.xtremepapers.com/community/members/dug.23386/
thanks in advance

use @withusername like "@Dug" to tag.

This question is just logic based.

Profit If more than 1 fail to work = -480$ (Since company gets no money and that's the price of the fireworks) Probability = 0.264 (part i)
Profit If 1 or less than 1 fail to work = 4500 - 480 = 4020 ----- Probability = (1-0.264=0.736)

Expected Profit = (0.264*-480) + (0.736*4020)
=2832 .. or 2830 (3sf)

 

[syed1995]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w10_qp_13.pdf
Please help me with no. 9 (b) (ii).. I really don't understand how it is solved in the marking scheme.
Thanks

Okay I don't understand it either.. I don't understand the question correctly but I will try anyway..

a= 100 d = -5
Sm=S(m+1)

Sm=n(2a-(n-1)d)/2
Sm=m(2(100)+5(m-1)/2
Sm=m(200+5m-5)/2
Sm=(195m+5m^2)/2

S(m+1)= m+1/2 * (2(100)+5(m+1-1))
S(m+1)= m+1 /2 * 200+5m
S(m+1)= (200m + 200 +5m^2+5m)/2

Sm=Sm+1
195m+5m^2=205m+200+5m^2
10m=200
m=20

Is that the correct answer?

 

[Alice123]

use @withusername like "@Dug" to tag.

This question is just logic based.

Profit If more than 1 fail to work = -480$ (Since company gets no money and that's the price of the fireworks) Probability = 0.264 (part i)
Profit If 1 or less than 1 fail to work = 4500 - 480 = 4020 ----- Probability = (1-0.264=0.736)

Expected Profit = (0.264*-480) + (0.736*4020)
=2832 .. or 2830 (3sf)

dint knw dat b4 syed1995
Anyways thanks

 

[parthrocks]

Hello syed1995 or anyone else please help me with this
these are sums of simple and compund interest but I am not getting it accurately...help me

 

[parthrocks]

this one too
syed1995

 

[parthrocks]

daredevil
this one is for you
plz asap

 

[parthrocks]

daredevil

 

[parthrocks]

anyone last one