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Author Topic: IGCSE MATHS Doubts  (Read 120719 times)

Offline ksitna

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Re: IGCSE MATHS Doubts
« Reply #885 on: May 18, 2010, 04:16:02 pm »
i dont get how they did this

Factorise completely m^4n ? 16n^5.
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Offline Adzel

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Re: IGCSE MATHS Doubts
« Reply #886 on: May 18, 2010, 04:19:51 pm »
same paper A@di Q4 part (f), Q5 part (b) + explaination...please  :)
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Offline Vin

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Re: IGCSE MATHS Doubts
« Reply #887 on: May 18, 2010, 04:21:03 pm »
Quote from: Adzel on May 18, 2010, 02:56:34 pm
O/N 2004 04 Q3 part (b) and (c) + explaination.....please  :)

this one is quite easy ..

3 a) V= pi * r2 *h
= pi * 402 *110
=552920.3
=553000 cm3

b) in this one water comes out at the speed of 14 cm/s through 1.6 cm2

so 14 * 1.6 volume of water comes out if the pipe
= 22.4 cm3/sec

meaning 22.4 cubic cms of water will pass every sec .. so how long does it take to fill the cylinder ..

so time taken would be
553000
--------
  22.4
=24687.5 sec / 60
= 411.45833333 mins /60
= 6.8576389 hrs
=6 hrs 51 mins


c) in this one the SA is given .. so ..
SA in mm = 70 * 100 * 100
= 700000 mm2

vol = SA * h
553000 = 700000 * h
h = 0.79 cm
= 7.9 mm

 ;)
« Last Edit: May 18, 2010, 04:49:39 pm by ~VIN1094~ »
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Offline $H00t!N& $t@r

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Re: IGCSE MATHS Doubts
« Reply #888 on: May 18, 2010, 04:25:21 pm »
need help with p4 O/N 2005 Q7c(ii)
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Offline Vin

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Re: IGCSE MATHS Doubts
« Reply #889 on: May 18, 2010, 04:27:30 pm »
Quote from: Shooting Star on May 18, 2010, 04:25:21 pm
need help with p4 O/N 2005 Q7c(ii)

ok gimme 2 mins

volume of pool = 1512 m3 * 100 *100 *100
=1512000000 cm3

volume of pipe = 6870 cm3

=1512000000 cm3
-----------------
    6870 cm3

=ans / 60(min) * 60(hrs) *24

=2.5473 days
=2 days 13 hrs

sorry net prob. !!
« Last Edit: May 18, 2010, 05:28:40 pm by ~VIN1094~ »
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Offline Adzel

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Re: IGCSE MATHS Doubts
« Reply #890 on: May 18, 2010, 04:31:13 pm »
Quote from: Adzel on May 18, 2010, 04:19:51 pm
same paper VIN Q4 part (f), Q5 part (b) + explaination...please  :)
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Offline Vin

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Re: IGCSE MATHS Doubts
« Reply #891 on: May 18, 2010, 04:48:23 pm »

imma hav my dinner till then try

https://studentforums.biz/index.php/topic,5575.msg167872.html#msg167872

aadi's made our lives easier ..
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Offline $H00t!N& $t@r

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Re: IGCSE MATHS Doubts
« Reply #892 on: May 18, 2010, 04:48:41 pm »
@VIN i think u made a mistake in answering q3b in the O/N 2004 ppr. the final answer is 6hours 51min cz when u convert 6.857638889 into hours and min you get 6 hours 51 min. the working is right tho. its just the final answer (the conversion)
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Offline Vin

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Re: IGCSE MATHS Doubts
« Reply #893 on: May 18, 2010, 04:50:08 pm »

yea sorry .. typo thanks =)
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Offline Ghost Of Highbury

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Re: IGCSE MATHS Doubts
« Reply #894 on: May 18, 2010, 04:57:48 pm »
Quote from: Adzel on May 18, 2010, 04:19:51 pm
same paper A@di Q4 part (f), Q5 part (b) + explaination...please  :)

4f) check the link given by VN to see the list. check the transformation matrix for stretch with y-axis invariant

(2 2) * (1.5 0)  = (3 2)
(5 2)    (0    1)    (7.5 2)

(2,2) --> (3,2)

(5,2) --> (7.5,2)

do the same with the last set of co-ordinate ..to get the image co-ordinates as (7.5,4)

ii) v already hav used it

   (1.5 0)
   (0   1)

5b)i) p is AO (check diagram)

    ACO is 51 degree, alternate interior to NAC.
  
    70/sin 90 = p/sin51

   p = 70sin51 = 54.4

bii) sqrt(54.4^2 + q^2) = 70

    q^2 = 70^2 - 54.4^2 = 1940.64

     q = 44.1
« Last Edit: May 18, 2010, 05:05:32 pm by A@di »
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Offline thenewkid™

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Re: IGCSE MATHS Doubts
« Reply #895 on: May 18, 2010, 05:02:30 pm »
can any1 pls help me wid may/june 2007 p4 q 3b (i)
Thanks
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Offline saleemsamer

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Re: IGCSE MATHS Doubts
« Reply #896 on: May 18, 2010, 05:05:46 pm »
can some1 plz explain jun 2007 p4 q 2f and 4 c-e  :)
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Offline Ghost Of Highbury

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Re: IGCSE MATHS Doubts
« Reply #897 on: May 18, 2010, 05:12:47 pm »
Quote from: thenewkid™ on May 18, 2010, 05:02:30 pm
can any1 pls help me wid may/june 2007 p4 q 3b (i)
Thanks

as they both are similar triangles, their respective sides are in proportion

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

simplify this equation to get

y^2 - 4y - 2 = 0
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Offline mdwael

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Re: IGCSE MATHS Doubts
« Reply #898 on: May 18, 2010, 05:19:33 pm »
They may sound a stupid question but to me its not. Its this question in summer 2000 paper 4 page 7 c(i) part it says "explain why the point (60,280) is on the curve?" this is the first time I face this kind of question, I was hoping someone could explain it to me
By the way the MS says its "end of interval is 60, 20+40+200" ??? ???
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Offline $H00t!N& $t@r

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Re: IGCSE MATHS Doubts
« Reply #899 on: May 18, 2010, 05:20:26 pm »
Quote from: ~VIN1094~ on May 18, 2010, 04:27:30 pm
ok gimme 2 mins

volume of pool = 1512 m3 * 100 *100 *100
=1512000000 cm3

volume of pipe = 6870 cm3

=1512000000 cm3
-----------------
    6870 cm3

=ans / 60(min) * 60(hrs) *24

=24.5473 days
=24 days 13 hrs

sorry net prob. !!


um.. i still dont get it... can u elaborate a bit more. By the way the ans in the ms is 2 days 13 hours
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