2018 Section B | Question 12

Probability of selecting a number based on divisiblity. An easy 2 mark question that appeared in 2018 CBSE class 10 maths board paper. Tests your understanding of when a probability of an event can be computed as (1 - probability of another event).

Question 12: An integer is chosen at random between 1 and 100. Find the probability that it is:

(i) divisible by 8

(ii) not divisible by 8

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Number of ways of choosing an integer at random between 1 and 100 = 98

Note 1 and 100 should not be included.

List of numbers between 1 and 100 that are divisible by 8:

8, 16, 32, 40, 48, 56, 64, 72, 80, 88, 96 = 12 numbers

Probability of number divisible by 8 = \\frac{\text{Number of integers between 1 and 100 divisible by 8}}{\text{Total number of integers between 1 and 100}})

Probability = \\frac{12}{98}) = \\frac{6}{49})

Because the set of numbers between 1 and 100 that are divisible by 8 and the set of numbers between 1 and 100 that are not divisible by 8 are

(a) mutually exclusive and

(b) collectively exhaustive,

Probability that the integer is not divisible by 8 = 1 - probability that the number is divisible by 8

1 - \\frac{6}{49}) = \\frac{43}{49})

**Note**: To be able to use the (1 - probability) method, the two events should be mutually exclusive and collectively exhaustive.

Class 10 Maths

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CBSE Class 10 Maths - 2022

- Real Numbers Revision Class
- Polynomials Revision Videos
- Linear Equations Revision Class
- Quadratic Equations Revision Class
- Arithmetic Progressions Revision Video
- Triangles Revision
- Coordinate Geometry Revision
- Trigonometry Revision Class
- Appl of Trigonometry
- Circles Revision Class
- Areas Related to Circles Revision Videos

1. Section A | 2018 CBSE Class 10 Maths 1 Mark **Questions 1 to 6**

2. Section B | 2018 CBSE Class 10 Maths 2 Mark **Question 7** | Real Numbers - Irrational Numbers

3. Section B | 2018 CBSE Class 10 Maths 2 Mark **Question 8** | Linear Equations in 2 variables

4. Section B | 2018 CBSE Class 10 Maths 2 Mark **Question 9** | Sum of Arithmetic Progressions

5. Section B | 2018 CBSE Class 10 Maths 2 Mark **Question 10** | Coordinate Geometry Section Formula

6. Section B | 2018 CBSE Class 10 Maths 2 Mark **Question 11** | Probability of Rolling 2 dice

7. Section B | 2018 CBSE Class 10 Maths 2 Mark **Question 12** | Probability of selecting numbers

8. Section C | 2018 CBSE Class 10 Maths 3 Mark **Question 13** | Real Numbers - LCM & HCF

9. Section C | 2018 CBSE Class 10 Maths 3 Mark **Question 14** | Polynomial Factorization

10. Section C | 2018 CBSE Class 10 Maths 3 Mark **Question 15A** | Coordinate Geometry - Parallelogram

11. Section C | 2018 CBSE Class 10 Maths 3 Mark **Question 15B** | Coordinate Geometry - Area of Triangles

12. Section C | 2018 CBSE Class 10 Maths 3 Mark **Question 16** | Quadratic Equations - Speed Time Distance

13. Section C | 2018 CBSE Class 10 Maths 3 Mark **Question 17** | Similar & Congruent Triangles

14. Section C | 2018 CBSE Class 10 Maths 3 Mark **Question 19** | Trigonometric Ratios

15. Section C | 2018 CBSE Class 10 Maths 3 Mark **Question 20** | Areas related to circles - sector area

16. Section C | 2018 CBSE Class 10 Maths 3 Mark **Question 21** | Surface Areas & Volumes - Cylinder, hemisphere and cone

17. Section C | 2018 CBSE Class 10 Maths 3 Mark **Question 22** | Statistics - Median

18. Section D | 2018 CBSE Class 10 Maths 4 Mark **Question 23** | Quadratic Equations _ Speed Distance Time

19. Section D | 2018 CBSE Class 10 Maths 4 Mark **Question 24** | Arithmetic Progressions

20. Section D | 2018 CBSE Class 10 Maths 4 Mark **Question 25A** | Equilateral & Right Triangles and Congruence

21. Section D | 2018 CBSE Class 10 Maths 4 Mark **Question 25B** | Pythagoram Theorem Proof

22. Section D | 2018 CBSE Class 10 Maths 4 Mark **Question 27** | Trigonometric Ratios & Identities

23. Section D | 2018 CBSE Class 10 Maths 4 Mark **Question 28** | Surface Area of Frustum

24. Section D | 2018 CBSE Class 10 Maths 4 Mark **Question 29** | Applications of Trigonometry - Heights & Distances

25. Section D | 2018 CBSE Class 10 Maths 4 Mark **Question 30** | Statistics - 2 Alternatives

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