In how many ways can a music store display four of the 10 best selling records
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Think about it like positions of a sports team. You have 10 players that you need to rearrange for your roster. You can repeat any of the players (or songs). So for position 1 (song 1) you have 10 choices because you haven't picked any to use yet. For spot 2, you already used one player (1 song) so you have 9 left to choose from. Keep going to slot 3, there are 8 remaining, then 7, 6, 5, 4, 3, 2, 1. this is also called FACTORIAL, or written at 10!. To find the answer you would multiply 10*9*8*7...*2*1. The reason you can do this is because you don't have any restrictions on what song goes in what place, but you also don't want to repeat any of the songs.
I hope that helped. Any other questions feel free to ask. Upvote • 0 Downvote Add comment More Report  David S. answered • 10/22/13 Tutor 4.9 (68)Wise Math Tutor About this tutor › About this tutor › Brittany...This would be a permutation problem. 10 things taken 10 at a time.
The answer would be 10! That is 10 factorial which is 10*9*8*7*6*5*4*3*2*1 = 3,628,800 Upvote • 0 Downvote Comment • 1 More Report David S. tutor In general a permutation is n!/(n-r)! where n is the number of things you have and r is how many you are taking at a time. 0! is agreed to = 1 |
