Page 147 - TB_6B
P. 147
Activity 4 Combinations
A combination is a selection of items in which the order of the items is not
important.
Find the number of possible ways to pick 2 representatives among Thomas,
Ricky, Ann, and Kate.
RepresentativeRepresentative RepresentativeRepresentative
ThomasAnnAnnThomas
Write all of the possible ways to pick 2 representatives among the 4 students.
Thomas, Ricky Thomas, Ann
Draw a diagram.
This represents that Thomas
and Kate are selected as
2 representatives.
How many ways can you pick 2 representatives?
Use the Fundamental Counting Principal.
There are 4 possible representatives. Once a student has been chosen, there
will be 3 possible representatives.
4 3 = 12 (ways)
But, the order of the students does not matter in combinations. “Thomas,
Ann” and “Ann, Thomas” are the same. So, divide 12 by 2 to eliminate any
repetitions.
12 2 = 6 (ways)
136
A combination is a selection of items in which the order of the items is not
important.
Find the number of possible ways to pick 2 representatives among Thomas,
Ricky, Ann, and Kate.
RepresentativeRepresentative RepresentativeRepresentative
ThomasAnnAnnThomas
Write all of the possible ways to pick 2 representatives among the 4 students.
Thomas, Ricky Thomas, Ann
Draw a diagram.
This represents that Thomas
and Kate are selected as
2 representatives.
How many ways can you pick 2 representatives?
Use the Fundamental Counting Principal.
There are 4 possible representatives. Once a student has been chosen, there
will be 3 possible representatives.
4 3 = 12 (ways)
But, the order of the students does not matter in combinations. “Thomas,
Ann” and “Ann, Thomas” are the same. So, divide 12 by 2 to eliminate any
repetitions.
12 2 = 6 (ways)
136
