# Class 9 NCERT Solutions Maths Chapter 15 - Probability

What’s the probability that a cricketer will hit a boundary? How to find the number of engineers living within a 7-km radius as per the given data? Finding the answers for similar questions is easy after you practise NCERT Solutions for CBSE Class 9 Mathematics Chapter 13 Probability. TopperLearning’s textbook solutions will help you grasp the techniques to solve probability exercises from your NCERT book.

Being able to understand probability will improve your logical thinking skills and help you in calculating the answers for simple problems. Utilise our CBSE Class 9 Maths video lessons and practice tests along with our textbook solutions to revise chapter basics easily.

Ex. 15.1

## Probability Exercise Ex. 15.1

### Solution 1

Number of times batswoman hits a boundary = 6

Total number of balls played = 30

Number of times that the batswoman does not hit a boundary = 30 - 6 = 24

Total number of balls played = 30

Number of times that the batswoman does not hit a boundary = 30 - 6 = 24

### Solution 2

Total number of families = 475 + 814 + 211 = 1500

(i) Number of families having 2 girls = 475

(ii) Number of families having 1 girl = 814

(iii) Number of families having no girl = 211

Thus, the sum of all these probabilities is 1.

Thus, the sum of all these probabilities is 1.

### Solution 3

Number of students born in August = 6

Total number of students = 40

Total number of students = 40

=

### Solution 4

Number of times 2 heads come up = 72

Total number of times the coins were tossed = 200

Total number of times the coins were tossed = 200

### Solution 5

Number of families surveyed = 2400

(i) Number of families earning Rs 10000 - 13000 per month and owning exactly 2 vehicles = 29

Required probability =

Required probability =

(ii) Number of families earning Rs 16000 or more per month and owning exactly 1 vehicle = 579

Required probability =

Required probability =

(iii) Number of families earning less than Rs 7000 per month and does not own any vehicle = 10

Required probability =

(iv) Number of families earning Rs 13000 - 16000 per month and owning more than 2 vehicles = 25

Required probability =

Required probability =

(v) Number of families owning not more than 1 vehicle = 10 + 160 + 0 + 305 + 1 + 535 + 2 + 469 + 1

+ 579 = 2062

Required probability =

### Solution 6

Total number of students = 90

(i) Number of students who obtained less than 20% marks in the test = 7

Required probability =

Required probability =

(ii) Number of students who obtained marks 60 or above = 15 + 8 = 23

Required probability =

Required probability =

### Solution 7

Total number of students = 135 + 65 = 200

(i) Number of students who like statistics = 135

P(student likes statistics) =

P(student likes statistics) =

(ii) Number of students who do not like statistics = 65

P(student does not like statistics) =

### Solution 8

Total number of engineers = 40

(i) Number of engineers living at a distance of less than 7 km form their place of work = 9

Required probability =

(i) Number of engineers living at a distance of less than 7 km form their place of work = 9

Required probability =

(ii) Number of engineers living at a distance of more than or equal to 7 km from their place of work

= 40 - 9 = 31

Required probability =

Required probability =

(iii) Number of engineers living within a distance of km from her place of work = 0

Required probability = 0

Required probability = 0

### Solution 11

Total number of bags = 11

Number of bags containing more then 5 kg of flour = 7

Required probability =

Number of bags containing more then 5 kg of flour = 7

Required probability =

### Solution 12

Number days for which the concentration of sulphur dioxide was in the

interval of 0.12 - 0.16 = 2

Total number of days = 30

Required probability =

Total number of days = 30

Required probability =

### Solution 13

Number of students having blood group AB = 3

Total number of students = 30

Required probability =

Total number of students = 30

Required probability =