SOLUTION: 2 bananas are to be selected from a group of 8. In how many ways can this be done?
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Question 1085261: 2 bananas are to be selected from a group of 8. In how many ways can this be done?
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
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 28
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 = 28
which is an alternative way to get the same answer
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