Question 1085261
<font color="black" face="times" size="4">We have two slots to fill: Slot A, Slot B


There are 8 choices for slot A


There are 7 choices for slot B


There are 8*7 = 56 permutations possible. This would be the answer if order mattered.


Since order does not matter, we must divide that result by 2 to get 56/2 = 28


We divide by two to correct for double-counting.


The final answer is <font color=red>28</font>


Side Note: we can use the combination formula to get


n C r = (n!)/(r!*(n-r)!)
8 C 2 = (8!)/(2!*(8-2)!) ... plug in n = 8 and r = 2
8 C 2 = (8!)/(2!*6!)
8 C 2 = (8*7*6!)/(2!*6!)
8 C 2 = (8*7)/(2!)
8 C 2 = (8*7)/(2*1)
8 C 2 = 56/2
8 C 2 = <font color=red>28</font>


which is an alternative way to get the same answer</font>