Question

If the order of selection is considered relevant, in how many ways can k objects be selected from a set of n objects?

Answer 1

hi,

You have to use a formula which is known as of binomial coefficient which is :

k among n is : C ( n /k) = n! / k! ( n-k)!

! = factorial

ex : 5 object among 8 is : C ( 8/5 ) = 8 ! / 5! * ( 8-5) !

As 8! = 8*7*6*5*4*3*2*1 = 40 320

As 5! = 5*4*3*2*1 = 120

as 3 ! = 3*2*1 = 6

then : 40 320 / 120 * 6

40 320 / 720 = 56

Conclusion : there is 56 way to select 5 object among 8 of them.

ps : you can also use Pascal Triangle to do such a thing.