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Mathematics: Post your doubts here!

Minato112

Minato112

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ZainH said:
Not exactly, why are you equating the equation while finding the inverse?
This is what I did.

To find H inverse
Let y = h(x)

h(x)= 9-(x-3)^2
h(x)-9= (x-3)^2
*root*h(x)-9= x-3
[*root*h(x)-9]+3 = x

H inverse = [*root*h(x)-9]+3 where as yours and the MS's is "9-x" instead of "x-9"


EDIT: I undestand what you did, but why is my method wrong?
Click to expand...

"To find H inverse
Let y = h(x)

h(x)= 9-(x-3)^2
h(x)-9= - (x-3)^2

The '-'... U omitted it! :) Correction in red
 
princess787

princess787

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some body!!!! please help poor me!! i'm sitting on this question since morning! can anyone help me in 9709_w12_qp_31 question 10 ii
 
Sanis

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Hello for statistics p6 i am having difficulities for finding the variance .. it's equation is 1/n sigma (x-random number)^2 - mean^2 ... however the mean to be calculated differ sometimes i dnt know why, i need to find something called the coded mean not the ordinary mean .. I need help to know when should I have to place the coded mean in the mean to be deducted, rather than the ordinary .. take number 1 of this exam as example http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s07_qp_6.pdf .... http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_s07_ms_6.pdf

Thank You
 
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yubakkk

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pLz help this question. its from book.

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.​
 
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aleezay

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Kumkum said:
can someone pls help me with question 5 and 6bii) nd 6c
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_63.pdf
thnx in advance :)
Click to expand...

Q5.(i) Apply continuity correction. If u are rounding off a number to 84, it must be in the range 83.5<X<84.5. Now calculate the probability of the result ( by converting the data to normal distribution by subtracting mean from each value and dividing by standard deviation)

(ii) Simply calculate P(X>87)- no need to apply continuity correction since there is no mention of rounding off numbers. U will get 0.3282
now convert the data to binomial distribution: X - B(5,0.3282) and calculate the result for P(X=0) + P(X=1) (at most 1 out of 5 trials- I'm assuming you'd be knowing how to evaluate this expression)

(iii) Convert data to normal distribution
Fi{(k-82)/under root 126} - Fi(5/under root 126) = 0.3
The rest is all simple algebra.
Please let me know if you still have a confusion. :)
 
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aleezay

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Kumkum said:
can someone pls help me with question 5 and 6bii) nd 6c
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_63.pdf
thnx in advance :)
Click to expand...
Q. 5(b)(ii) The first digit has to be a 2 if we are to get a no. between 20,000 and 30,000. the no of ways the remaining 5 digits can be used= 5P4= 120
(c) The probability of placing a white tile ( or any other colored tile) first is 1/3. The second tile must not be white so P(not white)=1 - 1/3=2/3. The same goes for all the remaining 6 tiles i.e the probability of placing a tile would be 2/3 since it has to be different from the previous tile. Now multiply your result by 3 (since you can place any of white,black or grey tiles first).
I hope this helps :)
 
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aleezay

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According to some friends of mine, using ES series calculators will straightaway result in a deduction of 10 marks. Is this true?? :O
 
Kumkum

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aleezay said:
Q5.(i) Apply continuity correction. If u are rounding off a number to 84, it must be in the range 83.5<X<84.5. Now calculate the probability of the result ( by converting the data to normal distribution by subtracting mean from each value and dividing by standard deviation)

(ii) Simply calculate P(X>87)- no need to apply continuity correction since there is no mention of rounding off numbers. U will get 0.3282
now convert the data to binomial distribution: X - B(5,0.3282) and calculate the result for P(X=0) + P(X=1) (at most 1 out of 5 trials- I'm assuming you'd be knowing how to evaluate this expression)

(iii) Convert data to normal distribution
Fi{(k-82)/under root 126} - Fi(5/under root 126) = 0.3
The rest is all simple algebra.
Please let me know if you still have a confusion. :)
Click to expand...
aleezay said:
Q. 5(b)(ii) The first digit has to be a 2 if we are to get a no. between 20,000 and 30,000. the no of ways the remaining 5 digits can be used= 5P4= 120
(c) The probability of placing a white tile ( or any other colored tile) first is 1/3. The second tile must not be white so P(not white)=1 - 1/3=2/3. The same goes for all the remaining 6 tiles i.e the probability of placing a tile would be 2/3 since it has to be different from the previous tile. Now multiply your result by 3 (since you can place any of white,black or grey tiles first).
I hope this helps :)
Click to expand...
thank u sooo much!! it did help :) (y)
 
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Minato112

Minato112

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princess787 said:
can anyone help me in 9709_w12_qp_31 question 3 and 10 ii) ! please! :)
Click to expand...
3) sin(θ + 45◦) = 2 cos(θ − 30◦)
sin θ. cos 45 + cos θ. sin 45 = 2 [ cos θ.cos 30 + sin θ.sin 30]

cos 45 = (|2/2), sin 45 = (|2/2), cos 30 = (|3/2) and sin 30 = (1/2)

(|2/2) sin θ + (|2/2) cos θ = 2 [ (|3/2) cos θ + (1/2) sin θ ]
(|2/2) sin θ + (|2/2) cos θ = |3 cos θ + sin θ
(|2/2) sin θ - sin θ = |3 cos θ - (|2/2) cos θ
((|2/2) - 1) sin θ = (|3 - (|2/2)) cos θ

Dividing everywhere by cos θ,

tan θ = [ (|3 - (|2/2))/((|2/2) - 1) ]

θ = 180 - *tan inverse* - [ (|3 - (|2/2))/((|2/2) - 1) ] = 105.9

As for the question 10 (ii), if noone answers it, I'll do it.
Also Note that "|" is used for root
 
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