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

Qualification => Subject Doubts => IGCSE/ GCSE => Math => Topic started by: Ghost Of Highbury on May 17, 2009, 01:50:15 pm

Title: Math help !
Post by: Ghost Of Highbury on May 17, 2009, 01:50:15 pm

Hello all..
i'm stuck in 2008 oct/nov math paper 4 q 9)a)

i am not able to fin "r"
plz find attached paper
thank you

Title: Re: Math help !
Post by: Ghost Of Highbury on May 17, 2009, 01:54:00 pm

is anyone dere??

Title: Re: Math help !
Post by: astarmathsandphysics on May 17, 2009, 02:01:42 pm

Am not home until late. He someone else tries good

Title: Re: Math help !
Post by: X Abdulrahman X on May 17, 2009, 02:03:09 pm

notice at the top is says "100 students"

if u get p and q, u add up all the numbers inside the circles which should add up to 99, add 1 lonely guy left  :P

Title: Re: Math help !
Post by: Enia on May 17, 2009, 02:07:14 pm

for p you have to add 12+17+8 you get 37. subtract that from 42 (because they said 42 students like swimming)

Then they said 40 people like only ONE sport that means you add 20+8 (28) and subtract from 40

for r add everything in the circles (u get 99) than means only one person doesn't like any sports.

Title: Re: Math help !
Post by: joel on May 17, 2009, 02:15:47 pm

It says 42 students like swimming so
42=12+8+17+p
So p=5
40 students like only one sport so
40=q+20+8
So q=12
There are total 100 so add all the no the subtract from 100
you will get 1
r=1

Title: Re: Math help !
Post by: Ghost Of Highbury on May 17, 2009, 02:16:53 pm

ohh.tks a lot

Title: Re: Math help !
Post by: susman on May 17, 2009, 02:53:18 pm

and yeah what about the c and e part?
need help...
thanks in advance

Title: Re: Math help !
Post by: care on May 17, 2009, 03:03:00 pm

c)i) B' contains everything that is not in the B set. So, n(B')=8+p+q+r=26
c)ii) B?F contains 20, 25, 12, 17, p, q.
S' contains 20, 25, q, r.
(B?F)?S? contains elements that are contained in both - B?F and S'.
So, n((B?F)?S?)=20+25+q=57

Title: Re: Math help !
Post by: Ghost Of Highbury on May 17, 2009, 03:07:37 pm

i onle got c i and e

c)i) n(B') means you don't take the whole of set B into consideration...therefore u r left with p q 8 and r..add them up
= 26

e)the total no. of people who like basketball are 74...12 of them also like swimming and 25 of them also like futball...so 25+12=37
the probability 4 the 1st student is 37/74
the probability for the 2nd is 36/73
multiply them
and u get 18/73