Mathematics: Post your doubts here!

[muzzaml]

Hi everyone, just a question
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s11_qp_61.pdf
http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Mathematics%20%289709%29/9709_s11_ms_61.pdf


In question 6, when we are asked to estimate the mean, the mark scheme uses 50.5 as the midpoint for the first class. Can anyone explain why that is? In addition, if anyone has a good article on the different cases of finding the midpoint, that would be much appreciated. Most I've seen only tell you to take the higher and lower limit, which doesn't always seem to work for me.

Thanks

 

[Ayeshak93]

NOTE i am considering @ as thita

as u found out in part i ..
4Cos@ + 3Sin@ = 5Cos(@-0.6435)

5Cos(@-0.6435) = 2
Cos(@-0.6435) = 2/5
@ = Cos^-1(2/5) + 0.6435

@= 1.8028 radians
and
2(pie)-1.8028 = 4.48 radians

can't seem to grasp onto the last part tho

Thanks

 

[SitiPutri]

Hi everyone, just a question
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_61.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_ms_61.pdf
In question 6, when we are asked to estimate the mean, the mark scheme uses 50.5 as the midpoint for the first class. Can anyone explain why that is? In addition, if anyone has a good article on the different cases of finding the midpoint, that would be much appreciated. Most I've seen only tell you to take the higher and lower limit, which doesn't always seem to work for me.

Thanks

The first class is 1 - 100, right? So (100+1)/2 = 50,5

 

[hEbBoOo]

Solution of June 2011 P31 Q10 (i).
hEbBoOo

View attachment 40040 View attachment 40041 View attachment 40042 View attachment 40043 View attachment 40044

Wait but the marking scheme says something else I mean have a look http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_ms_31.pdf but it's weird the final is still the same .. I answered with partial fractions exactly your way and didn't continue as I saw the marking scheme having this weird solution. xD
Ps. You really deserve a KitKat.

 

[Rahma Abdelrahman]

Wait but the marking scheme says something else I mean have a look http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_ms_31.pdf but it's weird the final is still the same .. I answered with partial fractions exactly your way and didn't continue as I saw the marking scheme having this weird solution. xD
Ps. You really deserve a KitKat.

Hahah!! Okay.
The mark scheme says the same thing.
Btw how do we conclude in part (ii) that N approaches 1800?

 

[Talha Irfan]

nothing unles you multiply both sides (if any) by 2

no offence, but these type of messages consisting of emotions just spam the thread. I request you and others to please make the website look a platform for education, moderators should disable this option -_- it just irritates eyes and doesn't give the thread/website an appropriate interface. If theses types of messages would not have added, then this thread would have half of the pages covered.

 

[Fahm Deen]

Oct/Nov 2011/13 no.9(iii) Why is the range less than or equal to zero. Can anyone help!!

 

[A star]

no offence, but these type of messages consisting of emotions just spam the thread. I request you and others to please make the website look a platform for education, moderators should disable this option -_- it just irritates eyes and doesn't give the thread/website an appropriate interface. If theses types of messages would not have added, then this thread would have half of the pages covered.

bro you have every right to complain but you are doin one thing wrong
1) complain to the admins not me they can remove the option
2) pm would have been better

 

[daredevil]

no offence, but these type of messages consisting of emotions just spam the thread. I request you and others to please make the website look a platform for education, moderators should disable this option -_- it just irritates eyes and doesn't give the thread/website an appropriate interface. If theses types of messages would not have added, then this thread would have half of the pages covered.

ummm.... wow! u must be a superhero or something. becz i for one know that if i have to reply on this thread with pure dry study stuff i will never be able to actually study. for most people that i know, we are regularly following the threads and between all the studying we do, we actuallly joke with each other and tease each other between the questions and it kinda keeps the thread alive. at least for me. its refreshing... and one of the reasons we answer each others' questions is i think bcz we actually talk to each other and are kinda even friends here!
do practice this routine and ask questionss... get involved... i think u'll like this )
when i need straight on info without no extra stuff i usually click up a website or the xtremepapers revision section.
Best of Luck (Y)

 

[psychiatrist]

I am very dull at maths............................pls smeone hlp me out

 

[moonangel996]

Can someone help me please ??
1) http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s10_qp_31.pdf Question 9
2) http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w12_qp_31.pdf Question 7
3) http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w11_qp_33.pdf Question 8 and 10
i need help please its urgent and iam really scared . Thank you in advance
2

 

[Talha Irfan]

bro you have every right to complain but you are doin one thing wrong
1) complain to the admins not me they can remove the option
2) pm would have been better

does the change has always to be forcefully implemented. Can't it come from within the community itself!

 

[cool Asviva]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w12_qp_41.pdf

please someone explain the question# 6ii.

P.E loss= gain in K.E + Workdone by resistance (Also, explain why workdone by resistance added?)
thanks in advance

 

[A star]

no offence, but these type of messages consisting of emotions just spam the thread. I request you and others to please make the website look a platform for education, moderators should disable this option -_- it just irritates eyes and doesn't give the thread/website an appropriate interface. If theses types of messages would not have added, then this thread would have half of the pages covered.

look bro you are the first one to complin about this no one else has complained yet. I would have gladly done it if it caused a general annoyance to people. And if you think this a VERY FORMAL sight just check out the languages used in other threads. and if you are so annoyed make another thread for this topic on announcements get enogh support and you can convince every one and uptill now only you are annoyed -_-

 

[daredevil]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_41.pdf

please someone explain the question# 6ii.

P.E loss= gain in K.E + Workdone by resistance (Also, explain why workdone by resistance added?)
thanks in advance

beccz the actual formula is

Net WD = WD by driving force - WD against resistance = Gain in energy - Loss in energy

[^ the energies can be any energies.... normally they are kinetic energy and gravitational potential energy]

 

[Talha Irfan]

Answer is 1209600

 

[Talha Irfan]

look bro you are the first one to complain about this no one else has complained yet. I would have gladly done it if it caused a general annoyance to people. And if you think this a VERY FORMAL sight just check out the languages used in other threads. and if you are so annoyed make another thread for this topic on announcements get enough support and you can convince every one and up till now only you are annoyed -_-

bro, I am not annoyed, but rather giving a suggestion, and that doesn't definitely need a majority.

 

[itallion stallion]

View attachment 40180 View attachment 40180 View attachment 40180 View attachment 40180
Answer is 1209600

Let's suppose that x and y are the chemicals which can not be placed near the door.so place A,F,E,J not available for them,so to arrange them we have 6 places left so 6P2.for the rest chemicals there are 8 places left so 8P8.so
6P2 multiply by 8P8=1209600.

 

[Talha Irfan]

Let's suppose that x and y are the chemicals which can not be placed near the door.so place A,F,E,J not available for them,so to arrange them we have 6 places left so 6P2.for the rest chemicals there are 8 places left so 8P8.so
6P2 multiply by 8P8=1209600.

thanks but why the answer is not coming this way :
Total/without restrictions - (should be placed on one of those 4)
==> if should be placed then (4C2 (choose two of four sides) * 2! (switching) * 8! (remaining eight)) = 483,840
10! - 483,840 = 3,144,960
what is going wrong with this approach>?

 

[itallion stallion]

thanks but why the answer is not coming this way :
Total/without restrictions - (should be placed on one of those 4)
==> if should be placed then (4C2 (choose two of four sides) * 2! (switching) * 8! (remaining eight)) = 483,840
10! - 483,840 = 3,144,960
what is going wrong with this approach>?

U are considering that there are two chemicals only that should be placed on the four positions.but when we are arranging the rest we are placing two more on those 4 places!