Mathematics: Post your doubts here!

[Scafalon40]

Thank you sooooooooooooooo much for the Help, Jazaka Allah khairan!! May Allah S.W.T bless you with high grades Ameeen, and May Allah S.W.T have mercy on you and your family.
Okay to get the value answer Q10 U need to make sure u have done part b correctly..
it is in short, a circle in forth quadrant, and there is a line 1/4 pi below x axis and a line 1

Now in the sketch below. You see, the largest point is in purple point. And to find it first we find the length of blue line under the green lines, to this use pythagoras theorem , so the short blue line is √2^2 +2^2 = 2√ 2
now to find the blue line till the purple point add a radius , which is 2, 2+2√2
now to find the largest Real Number, we have to find the value of xaxis above the purple point,
we know the angle is 1/4pi
so cos (1/4pi) = adj/ 2+2√2
adj = 2+√2

Yeah I just got it! I just realised that I took 90 degrees to mean pi instead of 1/2pi
Thanks man, I appreciate it
And neat username: phyzac (fy-zc) rhymes with Issac (as in Newton). Cool

 

[PhyZac]

Can someone please explain Q2 part i & Q8 PART i to me? Please!
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w09_qp_32.pdf
THX

For question 2,

Well see for this, i got 3 and 4 (as in Mark Scheme) the way i understood the question was like, see, they need to find where is root, and find 2 consecutive (after each other) value of x, the only way is to try numbers in the equation, i tried 2 a -ve came, i tried 3 a -ve came, i tired 4 a +ve came, so this indicate a root lies between 3 and 4 (due to change in sign)

 

[Alice123]

Post your Mathematics doubts in this thread rosogolla993

 

[PhyZac]

hey..i need help with the last part of question 10 (b) i know how to sketch it and shade it but i cant find the max arg of z

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_32.pdf

See..the blue line is 3 ( to the centre)
and the purple line is 2 (the radius)
now the green line has the max arg, and makes 90 degrees with the radius
therefore
cos (x) = opp / hyp
sin x = 2/3
x = 0.729...
now add 1/2pi ( that is 90 degree)
u get 2.30

 

[applepie1996]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w06_qp_3.pdf
question 7 part 4
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w05_qp_3.pdf
question 7 part 3
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w04_qp_3.pdf
question 9 part 3
http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_w04_qp_3.pdf
question 10 please please solve it somebody !
PhyZac Rutzaba or anyone else

 

[trgirl]

hi everyone i have a question and i cannot find it can you explain how to solve this question??? :'(

"the mean of a certain normally distributed variable is 4 times the standard deviation. the probability that a randomly chosen value is greater than 5 is 0.15
find the mean and standard deviation????? but how????? i really do not understand mark scheme it says that z=1.036. but how?? where did it come from??? if you find it i will be sooooo happpy thanx in advance

 

[trgirl]

i

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w06_qp_3.pdf
question 7 part 4
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w05_qp_3.pdf
question 7 part 3
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w04_qp_3.pdf
question 9 part 3
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w04_qp_3.pdf
question 10 please please solve it somebody !
PhyZac Rutzaba or anyone else

have the same quetions as well :'(

 

[syed1995]

(i) Transform OCR in a right-angled triangle.
Thus, you will CR = x cm , OC = 20 - x cm
The angle (q) COR will be 0.6 rads.

we have hypotenuse and opposite, we use, sin q = CR/OC
= sin(06) = x/(20-x)

I guess, you can proceed now !

So Many O Level concepts recalled in just one post

 

[syed1995]

hi everyone i have a question and i cannot find it can you explain how to solve this question??? :'(

"the mean of a certain normally distributed variable is 4 times the standard deviation. the probability that a randomly chosen value is greater than 5 is 0.15
find the mean and standard deviation????? but how????? i really do not understand mark scheme it says that z=1.036. but how?? where did it come from??? if you find it i will be sooooo happpy thanx in advance

Always link the paper. So helping you is easier.

We need to take Phi Inverse of 0.15

P(X>5) = 0.15
P(z<-(5-4s)s) = -Phi^-1(1-0.15)
-(5-4s)/s = -Phi^-1(0.85)
-5+4s = -1.036s
5= 5.036s
s = 0.993


s = 0.993
mean = 4s
mean = 3.97

 

[Rutzaba]

guys my net is being damn slowwww so even if i do the explanation wont b able to upload it... will try though

 

[shezi1995]

please help me with question number 6(i). Link to the question is http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s07_qp_4.pdf

First you have to find the displacement of P which is equal to that of Q as is given. Integrating (3t-0.3t^2) with limits 10 and 0 gives you the displacement. Then simply assume greatest speed to be v and find area under graph given i.e 0.5 *v*10 and equate it with the displacement found. I think you can do all the computations now.

 

[InternationationalGuy]

Guys. I have a question. Will we be provided a formula sheet for the papers. and can anyone give me one for Paper 1 and 4 cuz i dont have them.

 

[Rutzaba]

Guys. I have a question. Will we be provided a formula sheet for the papers. and can anyone give me one for Paper 1 and 4 cuz i dont have them.

u mean MF9?

 

[~`Heba`~ :)]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s10_qp_43.pdf

#7 (ii) and (iii) urgently please

 

[unseen95]

First you have to find the displacement of P which is equal to that of Q as is given. Integrating (3t-0.3t^2) with limits 10 and 0 gives you the displacement. Then simply assume greatest speed to be v and find area under graph given i.e 0.5 *v*10 and equate it with the displacement found. I think you can do all the computations now.

thanks

 

[sma786]

Help please
http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_s07_qp_6.pdf
Question 3(a), where did we get the -1.282 in the markscheme for the equation?
Markscheme here : (http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_s07_ms_6.pdf)

 

[PhyZac]

Guys. I have a question. Will we be provided a formula sheet for the papers. and can anyone give me one for Paper 1 and 4 cuz i dont have them.

Yes we get it.
This is the syllabus, and go to page 31, You will see heading Pure Math, Mechanics, Statistic. Pure math has both 1 and 3. and Mech has both Mech1 & 2 same with Stat.
http://papers.xtremepapers.com/CIE/...d AS Level/Mathematics (9709)/9709_y13_sy.pdf

 

[PhyZac]

Help please
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s07_qp_6.pdf
Question 3(a), where did we get the -1.282 in the markscheme for the equation?
Markscheme here : (http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s07_ms_6.pdf)

See, they said that P(X > 5.2) = 0.9
-Φ(z) = 0.9
z = 1.282 [so from the Normal distribution table]
-z= -1.282
Very simplified, if u dont get ask.

 

[Dug]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w06_qp_3.pdf
question 7 part 4
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w05_qp_3.pdf
question 7 part 3
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w04_qp_3.pdf
question 9 part 3
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w04_qp_3.pdf
question 10 please please solve it somebody !
PhyZac Rutzaba or anyone else

Check the first link again. There is no part 4...

w05 qp 3
Q7 iii

Mark a point at (1, 2).
|z| = |z - 1 - 2i|
|z - (0 + 0i)| = |z - (1 + 2i)|
Construct a perpendicular bisector of (0, 0) and (1, 2).
----------------------------
w04 qp 3
Q9 iii

Put Q in m:
<2, 0, -1> = <-2, 2, 1> +t<-2, 1, 1>
From one equation, you get t = -2. Test the remaining two equations with this value. It should satisfy them.

PQ = <-2, -1, -3> (By putting s = 2)
Make a dot product with 'm' and see if the answer is zero.
-----------------------
w04 qp 3
Q10
i)
V = 1000h
dV/dh = 1000

dV/dt = 30 - k√h

dh/dt = dh/dV x dV/dt
dh/dt = (1/1000) (30 - k√h)

When h = 1, dh/dt = 0.02
0.02 = (1/1000) (30 - k)
k = 10

dh/dt = 0.01(3 - √h)

ii)
[(x - 3)/x] dx = 0.005 dt
(1 - 3/x) dx = 0.005 dt
x - 3ln|x| = 0.005t + c

When x = 3, t = 0
3 - 3ln3 = c

x - 3ln|x| = 0.005t + 3 - 3ln3
0.005t = x - 3 - 3ln|x| + 3ln3
t = 200(x - 3 + 3ln|3/x|)

iii)
x = 3 - √h
x = 3 - √4 = 1

t = 200(1 - 3 + 3ln|3/1|) = 259

 

[PANDA-]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s10_qp_43.pdf

#7 (ii) and (iii) urgently please

I second this if someone could reply to this would be great.