S1. Need help!

[destined007]

will someone please solve nov 2009 Q 5 for me and also explain how its done.

 

[ahmed t]

which varient?

 

[destined007]

1st variant. Paper 61

 

[Merdons Wolfman]

i dont know

 

[ahmed t]

well if it must be btwn 5000 and 6000 then it must be a four digit number
and the first number MUST be a 5
so all we do is put a 5 at the start then we must choose the last 3 numbers which will be
5P3 since order matters

hope it helps

and for the second part
also u must have a 5 at the start and choose the last three
but any of the 6 letters may be repeated
so it will be
6^3
idk wat the 1*6^3 means in the ms




part b)if there are more girls then boys then it could be
3 G and 2B that will be8C3 *6C2
4G and 1 B and 8C4 *6C1
or 5G and 8C5
add all these together

part ii) so u make them all in the team + all not in the team
so it will be
u must choose another 2 from 11 so that will be 11C2
or must choose 5 from 11 so that will be 11C5
plus them together

 

[ahmed t]

did u get it?

 

[destined007]

I didn't get a ii. Why have you done 6^3?

 

[ahmed t]

its an eqaution
if u have N numbers or letters and u want to choose x of them and they may be repeated then the number of ways is
N^x
so here we have 6 numbers and we want 3 of them since the first one must be 5
so it will be 6^3

 

[ahmed t]

chek this out
http://www.mathsisfun.com/combinatorics/combinations-permutations.html

the permutations with repetition

 

[destined007]

thanks. didn't know that.