Mathematics: Post your doubts here!

[immie.rose]

Can someone please explain Q1 (link given) to me? Please!
Answers are as follows:
(i) tan(π − x) = −k
(ii) tan(π /2 -x)=1/k
(iii) sinx =k/ √1+k^2 from 90° triangle.
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s10_qp_11.pdf

 

[Shreeram]

please help me with question number 10(b) in detail. Link to the question is http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_31.pdf

Hope this helps

 

[Shreeram]

Can someone please explain Q1 (link given) to me? Please!
Answers are as follows:
(i) tan(π − x) = −k
(ii) tan(π /2 -x)=1/k
(iii) sinx =k/ √1+k^2 from 90° triangle.
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s10_qp_11.pdf

Hope this helps

 

[PANDA-]

http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_s05_qp_1.pdf

Question 7, part (iii)

 

[Beaconite007]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s11_qp_13.pdf
Question 8's part (i), please? :x

 

[abruzzi]

Probability she is on time = p = 1-0.75-0.05
p= 0.2
q= 1-0.2 = 0.8
n=96

We will be using normal approximation to solve this question...

Using Normal Approximation To Binomial

mean = np = 96*0.2 = 19.2
SD = √npq = √96*0.2*0.8 = √15.36

P(X<20)
Continuity Correction P(X<19.5)
P(z<[19.5-19.2]/√15.36)
P(z<0.07654)
Check the value of z from the normal distribution table.
= 0.531


ii)
She eats a banana if early = 0.7
She doesn't eat if early = 0.3
She eats a banana if on time = 0.4
She doesn't eat if on time = 0.6
She doesn't eat a banana if late = 1

probability she is late and doesn't eat a banana = 0.75*1 = L-B'
probability she is on time and doesn't eat a banana = 0.2*0.6 = OT-B'
probability she is early and doesn't eat a banana = 0.05*0.3 E-B'


(Given She Doesn't Eat A Banana| She Is On Time) (B'|E)

It means that all conditions of (her not eating a banana) will go in the denominator while (her being on time and not eating the banana) will go in the numerator

OT-B'/(L-B' + E-B' + OT-B')

(0.2*0.6)/[(0.75*1) + (0.05*0.3) + (0.2*0.6)]

= 8/59 Answer

Thank you very much bro, you have really helped me here.

I have one more problem in the same paper. I don't understand how to solve qn no. 7 (b ii) and 7 (c).
Could you please help me understand the solutions?

Hope I'm not bothering you..

 

[shezi1995]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s05_qp_1.pdf

Question 7, part (iii)

It is 90 degree. You can draw a graph and look at the value for which the function is one to one.

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_13.pdf
Question 8's part (i), please? :x

Use tan=sin/cos first and then open the square. The combine the fraction and use sin^2=1-cos^2. Use the difference of squares identity and cut the '1-cosx' from the numerator and denominator. And you are done.

 

[PANDA-]

It is 90 degree. You can draw a graph and look at the value for which the function is one to one.

Okay, but that can't be the only to do it right?

 

[hardik]

second chapter
linear combination of random variables

Three discs are drawn at random from a box containing a number of red and blue discs.
the mean and variance of the number of blue discs drawn are 2 and 0.5 respectively.what are the mean and variance of the red discs drawn?

 

[Beaconite007]

Use tan=sin/cos first and then open the square. The combine the fraction and use sin^2=1-cos^2. Use the difference of squares identity and cut the '1-cosx' from the numerator and denominator. And you are done.

I did that, but I keep getting (cosx-1) instead of (1-cosx) in the numerator

 

[unseen95]

that

Hope this helps

's awesome, I appreciate your help.

 

[Scafalon40]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_33.pdf
Q 7 part (iii) please PhyZac Dug syed1995

 

[syed1995]

Thank you very much bro, you have really helped me here.

I have one more problem in the same paper. I don't understand how to solve qn no. 7 (b ii) and 7 (c).
Could you please help me understand the solutions?

Hope I'm not bothering you..

Your 7 c)

https://www.xtremepapers.com/commun...st-your-doubts-here.9599/page-336#post-495659

7 b ii) This is a tricky question read these words of the question carefully.. "if the order in which Jessica chooses the 4 packets is taken into account" meaning it's permutation

8 Packets .. 1 Chocolate Biscuits(Bs) 1 Custard Cream (Cu)

4 Need to be chosen given Bs and Cu have to be chosen..

Bs Cu _ _

there were 8 total .. now 2 of those 8 have been chosen remaining = 6 packets .. and 2 need to be chosen.. and then there are 4 places in which these 4 packets can be arranged in...

So answer should be 6C2 * (cuz 2 of the remaining 6 items need to be chosen) 4! (cuz there are 4 places where each packet can go)

6C2*4! = 15 * 24 = 360 Ways

 

[syed1995]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_33.pdf
Q 7 part (iii) please PhyZac Dug syed1995

No P3 here...

 

[abruzzi]

Your 7 c)

https://www.xtremepapers.com/commun...st-your-doubts-here.9599/page-336#post-495659

7 b ii) This is a tricky question read these words of the question carefully.. "if the order in which Jessica chooses the 4 packets is taken into account" meaning it's permutation

8 Packets .. 1 Chocolate Biscuits(Bs) 1 Custard Cream (Cu)

4 Need to be chosen given Bs and Cu have to be chosen..

Bs Cu _ _

there were 8 total .. now 2 of those 8 have been chosen remaining = 6 packets .. and 2 need to be chosen.. and then there are 4 places in which these 4 packets can be arranged in...

So answer should be 6C2 * (cuz 2 of the remaining 6 items need to be chosen) 4! (cuz there are 4 places where each packet can go)

6C2*4! = 15 * 24 = 360 Ways

Thank youuu!
May god bless you for all the help

 

[immie.rose]

Hope this helps

Thanks!! though you've used add/sub formulas , which aren't a part of my sylllabus (i'm not appearing for P3 this year) ,so could you pls explain further :
how does tanπ -tanx / 1+tanπ tanx = -tanx/1 ?
thanks in advance!

 

[shezi1995]

I did that, but I keep getting (cosx-1) instead of (1-cosx) in the numerator

(Cosx-1)^2 = (1-cosx)^2 because minus sign taken common becomes plus due to the square.

 

[syed1995]

Thanks!! though you've used add/sub formulas , which aren't a part of my sylllabus (i'm not appearing for P3 this year) ,so could you pls explain further :
how does tanπ -tanx / 1+tanπ tanx = -tanx/1 ?
thanks in advance!

Tan x = k

If you have read about the quadrants ..

then Tan is positive in the first and 3rd quadrant.

Pi = 180 Degrees..

Pi - x means 2nd quadrant = -tan x = -k

ii) Tan(Pi/2 - x) = cot x = 1/tanx = 1/k

iii) Tan x = perp/base = k
= k/1

find the hyp. via pythogoras.. Hyp = √(k^2 + 1)

Sin = Perp/Hyp
Sin x = k/√(k^2+1)

 

[shezi1995]

Okay, but that can't be the only to do it right?

Well this part follows the previous part of sketching the graph. Also it is an easier method.

 

[Rutzaba]

He must have been an amazing teacher!!

he was sooo awesome... 90 percent of students in his class got A* 7 percent A and 3 percent others.
he made m,e go from E in school to A* in the cie o levels maths and A in add maths paper.
though in stats he is not as awsome as in pure maths