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Combination |
Selection of objects in which the order is not important. |
n= 4, r= 3
Subtract term
n!=n* (n-1)!
a/b=.a /3!./.b /3!.
1!=1
Calculate quotient
n= 12, r= 3
Subtract term
n!=n* (n-1)!
n!=n* (n-1)!
n!=n* (n-1)!
a/b=.a /9!./.b /9!.
2!=2
Multiply
Calculate quotient
Combination |
Selection of objects in which the order is not important. |
n= 5, r= 2
Subtract term
n!=n* (n-1)!
n!=n* (n-1)!
a/b=.a /3!./.b /3!.
2!=2
Multiply
Calculate quotient
Combination |
Selection of objects in which the order is not important. |
Since there are 5 red balls, choosing 3 red balls from the jar is the same as choosing which 2 balls should be left within the jar. In Part B, we found that there are 10 ways of choosing 2 red balls. Therefore, there are also 10 ways of choosing 5-2 = 3 red balls.
There are three blue balls, so there is only 1 way of choosing three blue balls — we have to choose all of them.