Question

what does 6P4 stands for?

Answer 1

the general permutation formula is

n P r = (n!)/(n-r)!

if n = 6 and r = 4, then you get

6 P 4 = (6!)/(6-4)!

Answer 2

it is the number of \(4\)-permutations of a group of \(6\) distinct items

Answer 3

but the choices are 360 180 30 and 15

Answer 4

so if you had \(\{a,b,c,d,e,f\}\) it would count the number of permutations of groups of 4 of these e.g. \(abcd, acdf, abcf, bdef, \dots\)

Answer 5

huuuh?

Answer 6

$$6!/(6-4)!=6!/2!=6\times5\times4\times3=\dots$$

Answer 7

oh. i get it already ;)