Permutation (1 Viewer)

[ozidolroks]

Can someone please help me with this questions?

1. In how many ways can 6 people be arraged in a circle if only 2 particular people are always a) together b) separated ?

2. 6 P 2 ( 6 permuation 2) = 120 (answer is 3)

3. The number of arrangements of 2n +2 different objects taken n at a time is to the number of arrangements of 2n different objects taken n at a time as 14:5. Find the value of n.

Thanks heaps

 

[unwanted80]

Can someone please help me with this questions?

1. In how many ways can 6 people be arraged in a circle if only 2 particular people are always a) together b) separated ?

they can sit in 5! ways.

together = 4! x 2 = 48

separated = 5! - 4! x 2 = 72

 

[Timothy.Siu]

Can someone please help me with this questions?

1. In how many ways can 6 people be arraged in a circle if only 2 particular people are always a) together b) separated ?

2. 6 P 2 ( 6 permuation 2) = 120 (answer is 3)

3. The number of arrangements of 2n +2 different objects taken n at a time is to the number of arrangements of 2n different objects taken n at a time as 14:5. Find the value of n.

Thanks heaps

2. whats the question lol
3. (2n+2)Pn/2nPn=14/5
(2n+2)!n!/(2n)!(n+2)!=14/5
(2n+2)(2n+1)/(n+1)(n+2)=14/5
5(4n^2+6n+2)=14(n^2+3n+2)
6n^2-12n-18=0
n^2-2n-3=0
(n-3)(n+1)=0
n=3 since n>0