Q1 . How many lines can be formed in a plane containing 15 non colinear points?

1. 105

2. 120

3. 240

4. 48

Check Answer

Correct Answer is

105

SOLUTION

total non collinear points 15

lines formed would be 15c2

15x14=210/2 = 105

Q2 . how many triangles can be formed in a plane with 18 non collinear points?

1. 4096

2. 4896

3. 625

4. 1632

Check Answer

Correct Answer is

1632

SOLUTION

total non collinear points 18

no. of triangles formed 18c3

4896/3 = 1632

Q3 . how many diagonals does a octogen have?

1. 12

2. 15

3. 20

4. 21

Check Answer

Correct Answer is

20

SOLUTION

octogan has 8 sides

the diagonals of a polygon with n sides is nc2-n

8c2-8

20

Q4 . if there are 5 boys and 4 girls how can they be arranmged in a line if no 2 girls sit adjacent?

1. 4096

2. 2056

3. 2880

4. 1024

Check Answer

Correct Answer is

2880

SOLUTION

there are 5 boys and 4 girls

let the girls be arranged first and can be 4!

there will be 5 gaps created by the girls in between

boys can be arranged in 5! Ways

5! X 4!

=2880

Q5 . how to arrange 5 identical balls in 5 boxes with one ball in a box?

1. 5!

2. 5!x4!

3. 1

4. 20

Check Answer

Correct Answer is

1

SOLUTION

since there are 5 boxes and 5 balls are identical

1

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permutation and Combination solved problems part -4

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• Permutation and Combination solved problems part -1
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• Permutation and Combination solved problems part -5