Mathematics: Post your doubts here!

[weirdoatlarge77]

How do you solve this, :

Amalie makes a profit of 20% when she sells a shirt for $21.60.
Calculate how much Amalie paid for the shirt.

Thank you in advance.

 

[TheManiac]

How do you solve this, :

Amalie makes a profit of 20% when she sells a shirt for $21.60.
Calculate how much Amalie paid for the shirt.

Thank you in advance.

(100+20)/100 =1.2
1.2X=21.60
X=18

 

[Ahmed Al Hilali]

Hey ,
Can anyone help me ?
1)0580/21/O/N/08 Q 5

2) I dont remember in which paper is this question, but it says :
D,E and X are 2x2 matrices.
I is the identity 2x2 matrix.
i) Simplify DI .
ii) DX=E
Write X in terms of D and E .

3) 0580/21/M/J/08 Q10

4) 0580/22/M/J/10 Q17 C

Tomorrow is my MJ22 exam ! thats why i'm having a lot of questions

Thanks in advance

 

[Aishy Vimal]

hello could someone help me with o/n 2010 v22 question 16 b and q14! please please urgent :c

 

[TheManiac]

hello could someone help me with o/n 2010 v22 question 16 b!

16y^10 * 4y^-4 / 32y^7=64y^6 / 32y^7=2y^-1

 

[sundas]

Can you please tell me when to round off our answers to 3 significant figures and when not to? please reply quick
i have exam tomorrow thankyou

 

[TheManiac]

always use 3 s.f. ... but if they tell you different in assignment then do like they said

 

[MMK95]

how to tell the difference between shear and stretch??????? they look same to me

 

[weirdoatlarge77]

hello could someone help me with o/n 2010 v22 question 16 b and q14! please please urgent :c

Change the bases to 2, e.g. 16= 2^4

 

[mak kings]

cud u plz plz plz ..explain the following 2 minor doubts ..it wud b a GUD REVISION FOR U 2!! !!!
OCT/NOV -2011-P22- Q1 .... i get 08 30 (time) .wen i subtract!
OCT/NOV-2011-P23- Q23(b) ......y dnt v take the time in mins wen dividing???
THNX IN ADVANCE ...!!! have exam tomorow!!!!

 

[TheManiac]

cud u plz plz plz ..explain the following 2 minor doubts ..it wud b a GUD REVISION FOR U 2!! !!!
OCT/NOV -2011-P22- Q1 .... i get 08 30 (time) .wen i subtract!
OCT/NOV-2011-P23- Q23(b) ......y dnt v take the time in mins wen dividing???
THNX IN ADVANCE ...!!! have exam tomorow!!!!

1) 17:30-09:00= 08:30
08:30/15 min= 35
23)
b) Avr=(A1+A2) / 15
A= [40*5/2+(15-5)*40]/15 = 500/15=33.33

 

[sundas]

but what do they mean by "when answer is not exact only then round off"?? what do they mean by exact answer?

 

[TheManiac]

exact answer is answer that is same as one in mark scheme (answer that is most precise and that is fully correct)
but it is allowed to you to make little mistakes (to round) and your answer usually must be near to decimal
e.g. in mark scheme is 2.88, but your calculator writes 2.88973 you can round last number on 2.89
i think i helped you

 

[sundas]

sorry for bothering you again.
For bounds they usually don't round off the answer and for probability they don't simplify the fraction?
is that how its suppose to be done?
or should i round of all my answers to 3 sf?

 

[TheManiac]

always round your answer to 3 s.f. , but if they tell you to round it on 1 or 2 then do as they said

 

[sundas]

Thank you ...what grade did you get in math?? i am assuming you are one with it

 

[TheManiac]

i have test tomorrow

 

[sundas]

Good luck!

 

[omar gk]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Mathematics (0580)/0580_w12_qp_21.pdf
question 20 b
how to do it ??

 

[TheManiac]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Mathematics (0580)/0580_w12_qp_21.pdf
question 20 b
how to do it ??

it is very easy

fg(x) = f(g(x))= 4(g(x)+1) = 4((x^3/2-1)+1)=4(x^3/2)= 2x^3