Mathematics: Post your doubts here!

[syed1995]

Please answer this question​

For a biased cubical dice the probability of any particular score between 1 and 6 (inclusive) being obtained is inversely proportional to that score. Find the probability of scoring a 1.​

I don't know .. I think this is what it will be... What's the answer?

1 ----- 2 ----- 3 ---- 4 ---- 5 ---- 6
x/1 + x/2 + x/3+ x/4 + x/5 + x/6 = 1

49x/20 = 1
x = 20/49


Probability of 1 = x/1
= 20/49 Answer

 

[A star]

I don't know .. I think this is what it will be... What's the answer?

1 ----- 2 ----- 3 ---- 4 ---- 5 ---- 6
x/1 + x/2 + x/3+ x/4 + x/5 + x/6 = 1

49x/20 = 1
x = 20/49


Probability of 1 = x/1
= 20/49 Answer

what i thought at first thought but i dont know if it is rite

 

[salvatore]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s10_qp_12.pdf
Please help me with qn no. 11 (ii & iii).

I've tried to sketch the graph (Attachment)... please check if its correct. For (iii), I'm totally confused!

Thanks

 

[A star]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s10_qp_12.pdf
Please help me with qn no. 11 (ii & iii).

I've tried to sketch the graph (Attachment)... please check if its correct. For (iii), I'm totally confused!

Thanks

ii seems correct as all it required was a graph
iii basically it is asking for for those values of k for which the line y = k does not intersect each other so k>2 k<-3

 

[salvatore]

ii seems correct as all it required was a graph
iii basically it is asking for for those values of k for which the line y = k does not intersect each other so k>2 k<-3

For ii, the answer is k < 1, k > 7

 

[Abu mota]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w10_qp_43.pdf Q.4
Also: http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s10_qp_43.pdf
Q.6 ii and Q.7 ii and iii

plz help me, im terrible at mechanics.

 

[Abu mota]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s12_qp_11.pdf
Q.7bii and Q.9 iii

 

[Swechhya]

http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_w08_qp_3.pdf

question no. 9 please please please help :/

and

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s09_qp_3.pdf


question number 6

The parametric equations of a curve are
x = a cos^3 t, y = a sin^3 t,
where a is a positive constant and 0 < t < pie/2
(i) Express dy/dx in terms of t. [3]
(ii) Show that the equation of the tangent to the curve at the point with parameter t is
x sin t + y cos t = a sin t cos t.

I've done part one. How do you do part (ii) ?

please help! Thanks in advance

 

[A star]

can anyone help me by telling me how to find out angle between tangents and angle between tangents and x axis :/. for some reason i keep forgetting

 

[A star]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s10_qp_12.pdf
Please help me with qn no. 11 (ii & iii).

I've tried to sketch the graph (Attachment)... please check if its correct. For (iii), I'm totally confused!

Thanks

dude the curve you have drawn is completely wrong for one thing its axis is y=4 and amplitude is clearly 3 . hence redraw the curve and get the correct answer

 

[tanmaydube]

sagar65265 thanks a lot!!!!

 

[tanmaydube]

part (ii) PLEASE

Thank You!

 

[Farhan Chowdhury]

5 The weights of letters posted by a certain business are normally distributed with mean 20 g. It is
found that the weights of 94% of the letters are within 12 g of the mean.
(i) Find the standard deviation of the weights of the letters. [3]

Could someone please answer this and show ALL the steps? Thank you

 

[Dug]

View attachment 23574

part (ii) PLEASE

Thank You!

ii)
A = ⌡x² √(1 - x²) dx

x = sinΘ
dx = cosΘ dΘ

A = ⌡sin²Θ √(1 - sin²Θ) cosΘ dΘ
A = ⌡sin²Θ cos²Θ dΘ
A = ⌡(sinΘ cosΘ)(sinΘ cosΘ) dΘ
A = ⌡(½ sin2Θ)(½ sin2Θ) dΘ
A = ¼ ⌡sin² 2Θ dΘ

 

[Silent Hunter]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s12_qp_31.pdf

need help in Q10 first part

thank you

 

[tanmaydube]

Dug thanks a lot!

 

[Dug]

5 The weights of letters posted by a certain business are normally distributed with mean 20 g. It is
found that the weights of 94% of the letters are within 12 g of the mean.
(i) Find the standard deviation of the weights of the letters. [3]

Could someone please answer this and show ALL the steps? Thank you

__8(µ-12)____20(µ)____32(µ+12)__

P(8 > X > 32) = 0.94
P(X < 8) = P(X > 32) = 0.03

P(Z < -12/σ) = 0.03
1 - φ(12/σ) = 0.03
φ(12/σ) = 0.97
12/σ = 1.881
σ = 6.38

 

[applepie1996]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_31.pdf

need help in Q10 first part

thank you

okay so here goes

so the equation is 2 tan2x + 5 tan^2 x = 0 --------- (1)
you open up tan2x = 2tanx/1-tan^2 x
now substitute this in the equation numbered (1) and you get .......
2 ( 2tanx/1-tan^2 x ) + 5 tan^2 x = 0-----------(2)
now since the question says use tanx as "t" substitute tanx as t in equation (2)
so you get , 2( 2t / 1- t^2 ) + 5 t^2 = 0
then open up the bracket and remove the fraction by multiplying the whole equation with 1-t^2 you get........
4t + 5t^2 - 5t^4 = 0
take "t" as a common factor and you get .........
t(4 + 5t - 5t^3) = 0
so t=0 and 4 + 5t - 5t^3=0-----------3
rearrange equation 3 as 5t^3=4+5t then divide equation by 5 ............you get
t^3=0.8+t and then cube root the other side
and wallah.............you get the answer

 

[Alice123]

http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_s08_qp_3.pdf
sum1 help with Q9ii.... Dug syed1995

 

[immie.rose]

can anyone help me by telling me how to find out angle between tangents and angle between tangents and x axis :/. for some reason i keep forgetting

You need to find the gradients of both the tangents, and then use the formula: tan-1[m2-m1/1-(m2*m1)]
(where m2 and m1 are the gradients, and m2 is the bigger grad.)