Page 49 - Mathematics Class - XI

TOPIC - 6: Permutations and Combinations

ACTIVITY 6.1

OBJECTIVE
To find the number of ways in which three cards can be selected from given five cards.

MATERIAL REQUIRED

 Cardboard sheet  Sketch pen
 White chart papers  Cutter
 White sheet paper  Glue

PRE-REQUISITE KNOWLEDGE
1. Knowledge of counting the objects of the different arrangements or fundamental principle of counting.

PROCEDURE
1. Take a cardboard sheet and paste white chart paper on it.

2. From the cardboard, cut out 5 identical cards of convenient size and mark these cards as C , C , C , C
3
4
1
2
and C .
5
DEMONSTRATION
1. Select one card from the given five cards.

2. Let the first selected card be C . Then the other two cards from the remaining four cards can be C C , C C ,
1 2 3 2 4
C C , C C , C C and C C .
2 5 3 4 3 5 4 5
Thus, the possible selections are C C C , C C C , C C C , C C C , C C C and C C C .
1
1
3
2
1
5
1
3
2
4
2
4
1
4
5
5
1
3
Record these selections on a paper sheet.
3. Let the first selected card be C . Then the other two cards from the remaining four cards can be C C , C C ,
1
4
2
1
3
C C , C C , C C and C C .
4
3
3
1
5
5
5
4
Thus, the possible selections are C C C , C C C , C C C , C C C , C C C and C C C .
2 1 3 2 1 4 2 1 5 2 3 4 2 3 5 2 4 5
Record these selections on the same paper sheet.
4. Let the first selected card be C . Then the other two cards from the remaining four cards can be C C , C C ,
4
2
3
1
1
C C , C C , C C and C C .
1 5 2 4 2 5 4 5
Thus, the possible selections are C C C , C C C , C C C , C C C , C C C and C C C .
3 1 2 3 1 4 3 1 5 3 2 4 3 2 5 3 4 5
Record these selections on the same paper sheet.
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