Mathematics: Post your doubts here!

[Rizwan Javed]

Rizwan Javed one last doubt please
View attachment 60545

How on earth is this 6C3?
I know that seperating the Es, we are left with VNZULA, 6 letters, but how comes 6C3?

You are to select 4 letters. 1 E is already selected. so from the remaining 6 you have to select 3 more letters to complete that selection of 4 letters.

 

[techgeek]

You are to select 4 letters. 1 E is already selected. so from the remaining 6 you have to select 3 more letters to complete that selection of 4 letters.

thanks a lot!

 

[waqas123]

(iv) This part is a bit tricky. Here you have to consider a number of possible scenarios.
You are to select exactly 1 N.

So the selections can either contain:
1. Zero As
2. 1 A
3. 2As
OR
4. 3As

N***
^ You are to fill these places shown by asterisks.

First Consider the situation there are no A's. [N***] The possible number of selections from the letters remaining excluding all As will be 3C3.

Then consider the next situation: 1 A. [NA**] The number of possible selections will be : 3C2

Situation for exactly 2 As : [NAA*] This can be done in 3C1 ways.

Situation for exactly 3 As: [NAAA] There is only 1 way to do it, so possible selections are only 1.


Now sum up all these results to get the final answer: 3C3 + 3C2 + 3C1 + 1 = 8

Hence total number of possible selections are 8.

Why can't we write 6C3? Like 6 letters are left other than N so we just calculate possible combinations of the six by 6C3?

 

[Rizwan Javed]

Why can't we write 6C3? Like 6 letters are left other than N so we just calculate possible combinations of the six by 6C3?

Because it includes three As, so there'll be repetition. Like let's name these three As as : A1, A2, and A3.
Consider the 2nd and 3rd criteria i mentioned, now see there'll be repition:

N A1 * *
N A2 * *
N A3 * *

^ See, these are actually the same combinations. So it would be wrong!

Get it?

 

[Saad the Paki]

Ooh hey XPC is back working anybody know why it was down ? ( along with many other past paper Web sites )

 

[techgeek]

Ooh hey XPC is back working anybody know why it was down ? ( along with many other past paper Web sites )

probably some web-hosting provider problem, I guess

 

[The Sarcastic Retard]

 

[The Sarcastic Retard]

I am got 70% in As level (b) and now I am getting almost 60/75 in P3 and 40/50 in S2. Will I be able to get an A ?
Thanks.

 

[The Sarcastic Retard]

Is the answer (i) 2558.88 and (ii) 46758.30?

 

[techgeek]

What should I go for? S2 or M1?

 

[Binyamine]

What should I go for? S2 or M1?

M1 is easier if you have some Physics knowledge.

 

[ZohaKhan]

I know it's irrelevant here but please can someone direct me to someone who has given or would b appearing for socio this oct/nov?

 

[Binyamine]

M1 is easier if you have some Physics knowledge.

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[Thought blocker]

I have doubts in shading the complex number Z with two inequalities thingy questions :/ can aanyone help?

qwertypoiu
Rizwan Javed

 

[The Sarcastic Retard]

9709_w09_qp_31
Q7(iv) explain in detail.

 

[Thought blocker]

W11 33 paper question 10 part b solution

 

[Thought blocker]

I want to know the things removed from P3 and added to P3 in 2016 syllabus!

 

[Thought blocker]

View attachment 59509

shouldnt the perpendicular bisector and the circumferene of circle be drawn with broken line? as < sign is used?

 

[Thought blocker]

shouldnt the perpendicular bisector and the circumferene of circle be drawn with broken line? as < sign is used?

M.Omar

 

[Thought blocker]

https://www.facebook.com/photo.php?fbid=1767252093496855&set=gm.848445205290022&type=3&theater check this solution