IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => IGCSE/ GCSE => Math => Topic started by: theigstudent on May 10, 2009, 07:30:11 pm

Title: maths
Post by: theigstudent on May 10, 2009, 07:30:11 pm

plz help me with
Q11 in nov 04 pap 2   ???
Q19 b in nov 04 pap2 ???
Q21 c in nov 04 pap2 ???

could u plz tell me the method of solving these Qs

Title: Re: maths
Post by: theigstudent on May 10, 2009, 08:34:26 pm

help some 1 plz
its urgent

Title: Re: maths
Post by: emi on May 10, 2009, 08:55:32 pm

Q11 :  just place the numbers as they tell u the rest keep it in E

A = prime numbers  means  ( 41, 43, 47 )
B = Odd numbers means ( 45, 49 )
E = the numbers which are left (40, 42, 44,46,48 )

b) n (BnA')
 first fine BnA  = ( 45, 49, 41 ,43, 47 )  since prime numbers are odd too the will be same
now remove A from it  =  ( 45 , 49 )   these 2 are left

they want the number so answer is = 2

hope u understand that .. sry dono the rest yet

Title: Re: maths
Post by: astarmathsandphysics on May 10, 2009, 10:33:40 pm

Quote from: theigstudent on May 10, 2009, 07:30:11 pm

plz help me with
Q11 in nov 04 pap 2   ???
Q19 b in nov 04 pap2 ???
Q21 c in nov 04 pap2 ???

could u plz tell me the method of solving these Qs

40, 41, 42, 43, 44, 45, 46, 47, 48, 49
A={41,43,47}
B={ 45, 49}
E={40,42,44,46,48}

b)ans=2

19b)2pi(41-35)=12pi

21c)|AB|=|(3,5)|=

Title: Re: maths
Post by: emi on May 10, 2009, 10:43:08 pm

but a star ,, the b part answer is 2 in MS ??

Title: Re: maths
Post by: astarmathsandphysics on May 10, 2009, 10:50:06 pm

I know, I am just rushing through all the questions. I corrected my mistake.

Title: Re: maths
Post by: emi on May 10, 2009, 10:53:18 pm

thanks for helping us :)

Title: Re: maths
Post by: pisecs on May 10, 2009, 11:27:31 pm

Q.19 - so the whole distance of the inner lane is 400m~ and we have 2 semicircles which makes a full circle with a radius of 35m

a) what you have to find is the length of the two straght lines of the inner lane so just think that you're cutting off the semicircles on the two sides
let's suppose that the 2 lines are 2x and that is wot you have to find

2*pi*35 + 2x = 400
2x = 400 - (2*pi*35)
    = 180m

b) 1 lane = 1m wide, 6 lanes = 6m

35+6= 41(radius of the outer lane)
2*pi*41 + 180(the same from a part) = 437.65m

the questions asks for the difference so,

437.65 - 400 = 37.7m (3sf)


Q21. hmm~ dont really know how to explain by words but i'll try...

a) well, you see the arrow on AB? it's like this --->
so it means that the line goes from A to B, so with the vector (3), from A, you go 3 squares to the right on the x-axis and 5 squares up on y
                                                                                   (5)

so point B will be on (4,6) and from B you get C by moving 4 squares to the rght and 0 upwards so it will be (8,6)

b) after you get the answer to a part then this is really obvious, D will be on (5,1)

c) here you have to find the length of AB so you just have to use pythagora square root of 32+52

Title: Re: maths
Post by: astarmathsandphysics on May 10, 2009, 11:32:30 pm

For the running track 19a) the straight lengths are the same.

Title: Re: maths
Post by: theigstudent on May 10, 2009, 11:36:26 pm

all u people Thanks a lot
now i understand every thing