THIS PRESENTATION ILLUSTRATES PROBLEMS IN COMBINATIONS IN A SIMPLE STEP BY STEP METHOD. IT COULD BE USEFUL FOR GRADE 11 MATH STUDENTS, STUDENTS APPEARING FOR THE GRE AND ACT AND SAT. SO IF YOU NEED A QUICK, EASY OVERVIEW OF COMBINATIONS WATCH THE ACCOMPANYING VIDEO AS WELL.

1. COMBINATIONS
GRADE 11 MATH(2018)

2. PREVIEW
THIS VIDEO WOULD BE USEFUL TO GRADE 11 MATH STUDENTS.
THE CONCEPT OF COMBINATIONS IS INTRODUCED AND EXPLAINED.
A FEW SIMPLE PROBLEMS ARE ALSO DISCUSSED.

3. = number of
ways of selecting
r objects from n
objects
𝑛 𝐶1
= 𝑛

6. Find n , if

7. In how many ways can a football team of 11 players be selected from
16 players?

8. I) How many of them will include 2 particular players?
II) How many of them will exclude 2 particular players?
2 particular players have to be included.
The remaining 9 players can be selected from 14 players in

9. ii) 2 players are excluded.
We have to choose 11 out of 14 players.
Number of ways this can be done =

10. Out of 5 men and 2 women, a committee of 3 persons is to be formed
so as to include at least 1 woman. In how many ways can this be done?
Men. Women
5. 2

11. There are 12 points in a plane of which 5 are collinear. These points are
joined in pairs. Find the number of straight lines formed.
From 12 points , number of straight line segments =
The 5 collinear points form one line segment.

12. Number of straight lines =
We add 1 since the 5 collinear points form one line segment.

13. In how many ways can a team of 3 boys and 3 girls be selected from 5
boys and 4 girls?
Boys. Girls
5. 4

14. Seven points lie on a circle. How many chords can be formed by joining
these points
A chord is formed by joining 2 points on the circle.

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