Mathematics: Post your doubts here!

[Scafalon40]

I found this.http://ncalculators.com/math-worksheets/how-to-calculate-class-interval-arithmetic-mean.htm
errrrrrr........

 

[sma786]

daredevil ,i have a doubt
http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_s09_qp_6.pdf , in the markscheme (http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_s09_qp_6.pdf) where did they get 0.674 for question 1?

 

[daredevil]

daredevil ,i have a doubt
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s09_qp_6.pdf , in the markscheme (http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s09_qp_6.pdf) where did they get 0.674 for question 1?

ok i'm pretty sure i did this question for my mocks prep but i am totall null blank ryt now :O if anyone answers then tag me too .... it just isnt hitting me -_-

 

[daredevil]

I found this.http://ncalculators.com/math-worksheets/how-to-calculate-class-interval-arithmetic-mean.htm
errrrrrr........

so they havent made class boudaries here?! :O

 

[sma786]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s09_qp_6.pdf
Question 3, (ii), (73.5-80/5.36) -> answer is -1.211 who's Φ is 0.8871
in the markscheme they say, 1-Φ(answer), which would be 1-0.8871 = 0.1129, but the answer in markscheme is 0.8871, why?!

( daredevil)

 

[Esme]

I see a lot of stats related posts here, anyone up for answering P3 doubts ?

 

[Esme]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_32.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_ms_32.pdf

Q9 ii) I can't seem to get the answer, even though I think I'm integrating it right.
We have to integrate x lnx^2
I'm doing it by integration by parts but I don't get the answer as in the marking scheme..
Anyone? Please show me the workings

applepie1996

 

[Esme]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s12_qp_32.pdf
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s12_ms_32.pdf

Q7 iii) why is arg(1+2i) - arg(1-3i) = arg(u) ??

Anika Raisa ?

 

[Sanis]

any urgent helpers? :O

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w11_qp_33.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_ms_33.pdf

I need help in q1, q6ii), q10i) Thanks in advance

 

[sma786]

http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_s06_qp_6.pdf

Question 6, i and ii, how to get the answer?

 

[Dug]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_32.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_ms_32.pdf

Q9 ii) I can't seem to get the answer, even though I think I'm integrating it right.
We have to integrate x lnx^2
I'm doing it by integration by parts but I don't get the answer as in the marking scheme..
Anyone? Please show me the workings

applepie1996

ln(x²) is not the same as [ln(x)]². Try again using the latter!

 

[Dug]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s06_qp_6.pdf

Question 6, i and ii, how to get the answer?

i)
First round: 32 teams, 16 winners, 16 losers
These 16 losers play only one game as they are knocked out in the first round.

ii)
Second round: 16 teams, 8 winners, 8 losers
The 8 losers in this round play exactly two games. They qualify for the second round after winning in the first but then get defeated!

 

[sma786]

i)
First round: 32 teams, 16 winners, 16 losers
These 16 losers play only one game as they are knocked out in the first round.

ii)
Second round: 16 teams, 8 winners, 8 losers
The 8 losers in this round play exactly two games. They qualify for the second round after winning in the first but then get defeated!

thnksss!

 

[freezingfires]

(i)
So P(X=0) means when no blue is taken,
it will be
7/1o x 6/9 x 5/8 x 4/7 = 1/6
first 7 orange from 10 total, then 6 from 9 total (because one is taken) etc..

P(X=1)
(7x6x5x3) / (10x9x8x7) x 4 = 1/2
we will take 3 from orange so first 7 then 6 then 5 left, for blue we take once so only 3
down is total number, that is, 10 then 9 , 8 ,7
x4 because blue can be taken first second third or fourth

(ii)
for 0 we know 1/6
for 1 we know 1/2
for 2 it will be 4C2 x (3x2x7x6) / (10x9x8x7) = 3/10 [i take 4 combine 2 to get how many ways can we get 2 blues]
for 3 it will be 4C3 x (3x2x1x7) / (10x9x8x7) = 1/30

X=x..... || 0 || 1 || 2 |||| 3 |
P(X=x) |1/6|1/2|3/10| 1/30|

Thanks a lot PhyZac !!That was really helpful....May you pass with excellent grades .Ameen.I also posted a question in Physics thread any help will be highly appreciated

 

[Ashique]

daredevil ,i have a doubt
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s09_qp_6.pdf , in the markscheme (http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s09_qp_6.pdf) where did they get 0.674 for question 1?

daredevil
They told us that 225 out of the 900 cartons has more than 1002 milliliters. So what is the probability that a carton has more than 1002 milliliters? It's 225/900= 0.25. So if we were to standardize 1002 milliliters, you'd get a z value that would correspond to a probability of 0,25 in the normal distribution table. But you don't have 0.25 in the table, so you (1-0.25 = 0.75). So the probability that you would be looking for in the table is 0.75. Which is 0.674. Since the probability is GREATER than 1002, the sign won't change in this case.

 

[AlishaK]

Can someone please explain how question 8(full) is solved? Which steps must be included etc.

This paper

Did you get it? or u still need some help?! let me know, I'll explain you then

 

[Ashique]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s06_qp_6.pdf

Question 6, i and ii, how to get the answer?

i) If a team only plays one one game, it means they got out in the first round. With every new round, the number of teams halves. So if there if 16 teams in the second round, which means there were 32 teams in the first round. 32-16=16 teams

ii) If teams played exactly two matches, which means they got out in round two .We know there were 16 people who played round 2. 8 teams would make it to he next round
16-8= 8 teams.

 

[PhyZac]

I've watched the video. It still doesn't make sense. If you take the class boundaries as 0 and 9.5, you'll get the midpoint as 4.75, whereas the mark scheme clearly states it as 4.5. That's what I don't understand!!!!!!!!!!!!!!!!!!!!!!!!!

I found this.http://ncalculators.com/math-worksheets/how-to-calculate-class-interval-arithmetic-mean.htm
errrrrrr........

Well, May Allah S.W.T help you with this thing! Aameen.
I think it is a matter of acceptance.

 

[daredevil]

daredevil
They told us that 225 out of the 900 cartons has more than 1002 milliliters. So what is the probability that a carton has more than 1002 milliliters? It's 225/900= 0.25. So if we were to standardize 1002 milliliters, you'd get a z value that would correspond to a probability of 0,25 in the normal distribution table. But you don't have 0.25 in the table, so you (1-0.25 = 0.75). So the probability that you would be looking for in the table is 0.75. Which is 0.674. Since the probability is GREATER than 1002, the sign won't change in this case.

oooh thanks... i was thinking about subtracting some but lost my bearings so couldn't wrap my head around wat to subtract even though it was pretty clear... thanks a bunch

 

[daredevil]

ok look here:
P(A) = 1/3
P(B) = 5/9

are these events mutually exclusive??
plz give an explnation too like working and all cz i'm not sure if i'm doing it ryt...

also explain if they are independant events...
and are they exhaustive events...
again with the working and stuff. thanks a lot