In how many ways can you arrange six out of eight books on a shelf?

1 Answer
Mar 16, 2016

Answer:

I hope I am correct! 28 ways

Explanation:

This is a permutation question

The number of arrangements is #(n!)/((n-r)!r!)#

where
#n=8#
#r=6#

Giving
#color(brown)((n!)/((n-r)!r!))" "->" " color(blue)(( 8!)/((8-6)!6!)#

Always look for factorials that can be cancelled.

#" "(8xx7xxcancel(6!))/((2xx1)xxcancel(6!) ) #

#" "4xx7 = 28#