Mathematics: Post your doubts here!

[syed1995]

this one too
syed1995

sorry dude .. no idea about these questions .. i remember doing SI in O levels (No CI at all) but don't remember it that well to solve your question..

 

[daredevil]

Maths
Q 5 may june 2011 p11
Plz solve the second part for me

Q7 part ii

Q11 part iv

Pleaase solve...

 

[daredevil]

Ya

anyone last one

yaar sorry i dont know how to do compound interest.
I = PRT/100
Compound interest ka b formula le k uss mein values put ker k fekh lo difference ka expression bna k.

 

[daredevil]

daredevil

In q 6 calculate the interest by the PRT/100 formula and then add the principle to the interest to get the total amount to be paid after four years. That would be interest + original amount

 

[daredevil]

anyone last one

690 = I + P
I = 690 - P

690-P = R*3*X/100

Make a similar expression for 750 and then make a common subject in both equations and equate them.

 

[Jspake]

Okay I don't understand it either.. I don't understand the question correctly but I will try anyway..

a= 100 d = -5
Sm=S(m+1)

Sm=n(2a-(n-1)d)/2
Sm=m(2(100)+5(m-1)/2
Sm=m(200+5m-5)/2
Sm=(195m+5m^2)/2

S(m+1)= m+1/2 * (2(100)+5(m+1-1))
S(m+1)= m+1 /2 * 200+5m
S(m+1)= (200m + 200 +5m^2+5m)/2

Sm=Sm+1
195m+5m^2=205m+200+5m^2
10m=200
m=20

Is that the correct answer?

Damn.. that seemed pretty easy huh.

Its the correct answer.. thanks a lot!

 

[parthrocks]

690 = I + P
I = 690 - P

690-P = R*3*X/100

Make a similar expression for 750 and then make a common subject in both equations and equate them.

yes true!thanks and ya no problem syed1995
and daredevil attach the paper if possible i can help you

 

[daredevil]

yes true!thanks and ya no problem syed1995
and daredevil attach the paper if possible i can help you

 

[parthrocks]

Its quite simple for the question 7 part 2 just do it like
3/(1 + 2x)^2 < 1/3 and then solve for x in the next step you will get like this

(1 + 2x)^2 (>)9
then
once when you solve it using the (a+b)^2 formulae you will get it like 4x^2 + 4x +1>9
you will get like
4x^2 +4x -8 and then solve it quadratically......ok get it like x > 1, x < –2 ok gt it?

 

[syed1995]

Maths
Q 5 may june 2011 p11
Plz solve the second part for me

Q7 part ii

Q11 part iv

Pleaase solve...

5ii is really simple .. you just gotta substitute y=sin^2(Theta).

The equation 2sin^4(Theta)+Sin^2(Theta)-1=0 becomes 2y^2 + y -1 =0

2y^2 + y -1 =0

2y^2 +2y -y -1 = 0

2y(y+1)-1(y+1)=0
(2y-1)(y+1)=0
y=1/2 or y=-1

sin^2(Theta)=1/2 or -1
Sin(Theta)=√1/2 or √-1 (which isn't possible.)
Theta= Sin-1(√1/2)
Theta=45

Thetha = 45 Degrees and 135 Degrees (Since Sin is only positive in first and 2nd quadrant)

 

[syed1995]

Damn.. that seemed pretty easy huh.

Its the correct answer.. thanks a lot!

no problem mate!

 

[syed1995]

Maths
Q 5 may june 2011 p11
Plz solve the second part for me

Q7 part ii

Q11 part iv

Pleaase solve...

Q11 iv .. what's hard in it?

find inverse of f(x) and put g(x) into that inverse equation.

y= 2x +1
(y-1)/2=x

f-1(x)=(x-1)/2

f-1(g(x))= (x^2-2-1)/2
=(x^2-3)/2

 

[skinnyboyfat]

can someone please tell me what is "List of formulae (MF9) " stated on P1 under Additional materials ????

 

[Jspake]

can someone please tell me what is "List of formulae (MF9) " stated on P1 under Additional materials ????

There is a specific formula booklet which contains various mathematical formulae.
Students can refer to this booklet during examinations.

 

[Mayedah]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w11_qp_13.pdf. Is there any other method like through y derivative or any thing else other than the mark scheme ! This is a confusing question !

 

[Alice123]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w11_qp_63.pdf
no 6 Dug syed1995 anyone
thanks in advance

 

[skinnyboyfat]

There is a specific formula booklet which contains various mathematical formulae.
Students can refer to this booklet during examinations.

Thanks a lot
can i find it somewhere online??? for reference ????

 

[Ashique]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_63.pdf
no 6 Dug syed1995 anyone
thanks in advance

PART i)
The question said that only Rhesus + is taken, so if we note down the probabilities for all the Rhesus+=
A+= 0.35
B+= 0.08
AB+= 0.03
O+= 0.37

Now, what you do is, you draw up a probability distribution table for the Rhesus + values. So first of all calculate the total probability of the Rhesus + values= 0.35+0.08+0.03+037= 0.83

So what will the probability of selecting a person with the blood group of A+? It will be 0.35/0.83. For B+ 0.08/0.83. For AB+ 0.03/0.83 and for O+ 0.37/.83.

The question asks to find the probability that fewer than 3 are group O+. Now, you have think. It can either be O+, or it can't be O+. So the immediate thought that should hit you is that you have to use a binomial approximation. So the probability of a success (The probabolity of selecting a person who is O+) is 0.37/.83. The probability of a failure (Not selecting a person who's O+) is (0.35+0.08+0.03)/0.83= .46/.83
So P(X<3) means that you have to use the binomial expansion for 0, 1 and 2.
9C0*(.37/.83)^0*(0.46/.83)^9 + 9C1*(.37/.83)^1*(0.46/.83)^8 + 9C2*(.37/.83)^2*(0.46/.83)^7
=0.1555= 0.156

PART ii)
Now the question asks you to find a probability that involves a huge number. Using a binomial approximation can be very time consuming. You could use a normal approximation (np>5)
You have to find the probabily that more than 60 people are group A+. For using normal approximation, firstly, you have standardize 60.5. For which you need the mean and the standard deviation.
To find the mean we use np (total number* probability), and to find the variance we use npq (total number*probability*(1-probability))
So mean= np= 150*.35=52.5
And variance= npq= 150*.35*(1-.35)= 34.125
So standard deviation= square root of variance= 5.84

So now you have to standardize 60 i.e P(X>60). However, the questions asks you to find the probability of MORE than 60 people. so you have to take P(X>60.5).
Now first of all standardize 60.5 using (60.5-mean)/(standard deviation)
(60.5-52.5)/5.84
This give yous the Z value which is 1.369
Now you are to find P(X>1.369) using the normal distribution table. The value corresponding to 1.369 is 0.3145. Since you have to find the probability greater than 0.329, you have to subtract 1 from the probability
So 1-03145= 0.0855


Hope this helps!

 

[Ashique]

Thanks a lot
can i find it somewhere online??? for reference ????

Refer to any syllabus. The section is titled "List of formulae and tables of the normal distribution".

 

[syed1995]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_13.pdf. Is there any other method like through y derivative or any thing else other than the mark scheme ! This is a confusing question !

Which Question?