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RD Sharma solutions for Class 9 Mathematics chapter 25 - Probability

Mathematics for Class 9 by R D Sharma (2018-19 Session)

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RD Sharma Mathematics Class 9 by R D Sharma (2018-19 Session)

Mathematics for Class 9 by R D Sharma (2018-19 Session)

Chapter 25: Probability

Ex. 25.1Others

Chapter 25: Probability Exercise 25.1 solutions [Pages 13 - 15]

Ex. 25.1 | Q 1 | Page 13

A coin is tossed 1000 times with the following frequencies:
Head: 455, Tail: 545
Compute the probability for each event.

Ex. 25.1 | Q 2 | Page 13

Two coins are tossed simultaneously 500 times with the following frequencies of different outcomes:
Two heads: 95 times
One tail: 290 times
No head: 115 times
Find the probability of occurrence of each of these events.

Ex. 25.1 | Q 3 | Page 13

Three coins are tossed simultaneously 100 times with the following frequencies of different outcomes:

Outcome: No head One head Two heads Three heads
Frequency: 14 38 36 12

If the three coins are simultaneously tossed again, compute the probability of:
(i) 2 heads coming up.
(ii) 3 heads coming up.
(iii) at least one head coming up.
(iv) getting more heads than tails.
(v) getting more tails than heads.

Ex. 25.1 | Q 4 | Page 13

1500 families with 2 children were selected randomly and the following data were recorded:

Number of girls in a family 0 1 2
Number of families 211 814 475

 

If a family is chosen at random, compute the probability that it has:
(i) No girl
(ii) 1 girl
(iii) 2 girls
(iv) at most one girl
(v) more girls than boys
Ex. 25.1 | Q 5 | Page 13

In a cricket match, a batsman hits a boundary 6 times out of 30 balls he plays.
(i) he hits boundary
(ii) he does not hit a boundary.

Ex. 25.1 | Q 6 | Page 13

The percentage of marks obtained by a student in monthly unit tests are given below:

Unit test: I II III IV V
Percentage of marks obtained: 69 71 73 68 76

 

 


Find the probability that the student gets:
(i) more than 70% marks
(ii) less than 70% marks
(iii) a distinction

Ex. 25.1 | Q 7 | Page 14

To know the opinion of the students about Mathematics, a survey of 200 students was conducted. The data is recorded in the following table:

Opinion: Like Dislike
Number of students: 135 65

 

Find the probability that a student chosen at random (i) likes Mathematics (ii) does not like it.

Ex. 25.1 | Q 8 | Page 14

The blood groups of 30 students of class IX are recorded as follows:

A B O O AB O A O B A O B A O O
A AB O A A O O AB B A O B A B O
A student is selected at random from the class from blood donation, Fin the probability that the blood group of the student chosen is:
(i) A
(ii) B
(iii) AB
(iv) O
Ex. 25.1 | Q 9 | Page 14

Eleven bags of wheat flour, each marked 5 Kg, actually contained the following weights of flour (in kg):
4.97, 5.05, 5.08, 5.03, 5.00, 5.06, 5.08, 4.98, 5.04, 5.07, 5.00
Find the probability that any of these bags chosen at random contains more than 5 kg of flour.

Ex. 25.1 | Q 10 | Page 14

Following table shows the birth month of 40 students of class IX.

Jan Feb March April May June July Aug Sept Oct Nov Dec
3 4 2 2 5 1 2 5 3 4 4 4
Find the probability that a student was born in August.
Ex. 25.1 | Q 11 | Page 14

Given below is the frequency distribution table regarding the concentration of sulphur dioxide in the air in parts per million of a certain city for 30 days.

Conc. of SO2 0.00-0.04 0.04-0.08 0.08-0.12 0.12-0.16 0.16-0.20 0.20-0.24
No. days: 4 8 9 2 4 3
 

Find the probability of concentration of sulphur dioxide in the interval 0.12-0.16 on any of these days.

Ex. 25.1 | Q 12 | Page 14

A company selected 2400 families at random and survey them to determine a relationship between income level and the number of vehicles in a home. The information gathered is listed in the table below:
 

Monthly income:
(in Rs)
Vehicles per family
0 1 2 Above 2
Less than 7000
7000-10000
10000-13000
13000-16000
16000 or more
10
0
1
2
1
160
305
535
469
579
25
27
29
29
82
0
2
1
25
88


If a family is chosen, find the probability that family is:
(i) earning Rs10000-13000 per month and owning exactly 2 vehicles.
(ii) earning Rs 16000 or more per month and owning exactly 1 vehicle.
(iii) earning less than Rs 7000 per month and does not own any vehicle.
(iv) earning Rs 13000-16000 per month and owning more than 2 vehicle.
(v) owning not more than 1 vehicle
(vi) owning at least one vehicle.

Ex. 25.1 | Q 13 | Page 15

The following table gives the life time of 400 neon lamps:

Life time
(in hours)
300-400 400-500 500-600 600-700 700-800 800-900 900-1000
Number of lamps: 14 56 60 86 74 62 48

A bulb is selected of random, Find the probability that the  the life time of the selected bulb is:
(i) less than 400
(ii) between 300 to 800 hours
(iii) at least 700 hours.

Ex. 25.1 | Q 14 | Page 15

Given below is the frequency distribution of wages (in Rs) of 30 workers in a certain factory:
 

Wages (in Rs) 110-130 130-150 150-170 170-190 190-210 210-230 230-250
No. of workers 3 4 5 6 5 4 3


A worker is selected at random. Find the probability that his wages are:
(i) less than Rs 150
(ii) at least Rs 210
(iii) more than or equal to 150 but less than Rs 210.

Chapter 25: Probability solutions [Page 16]

Q 1 | Page 16

Define a trial.

 
Q 2 | Page 16

Define an elementary event.

 
Q 3 | Page 16

Define an event.

 
Q 4 | Page 16

Define probability of an event.

 
Q 5 | Page 16

A big contains 4 white balls and some red balls. If the probability of drawing a white ball from the bag is `2/5`, find the number of red balls in the bag.

Q 6 | Page 16

A die is thrown 100 times. If the probability of getting an even number is `2/5` . How many times an odd number is obtained? 

Q 7 | Page 16

Three coins are tossed simultaneously 200 times with the following frequencies of different outcomes:

Outcome 3 heads 2 heads 1 head No head
Frequency 23 72 77 28

Find the probability of getting at most two heads. 

Q 8 | Page 16

 what is the probability of getting at least two heads?

 

Chapter 25: Probability solutions [Pages 16 - 17]

Q 1 | Page 16

Mark the correct alternative in each of the following:
The probability of an impossible event is

  • 1

  • 0

  •  less than 0

  •  greater than 1

Q 2 | Page 16

The probability of a certain event is

  • 0

  • 1

  • greater than 1

  • less than 0

Q 3 | Page 16

The probability an event of a trial is

  • 1

  • 0

  • less than 1

  • more than 1

Q 4 | Page 16

Which of the following cannot be the probability of an event?

  • `1/3`

  • `3/5`

  • `5/3`

  • 1

Q 5 | Page 16

Two coins are tossed simultaneously. The probability of getting atmost one head is

  • `1/4`

  • `3/4`

  • `1/2`

  • `1/4` 

Q 6 | Page 17

A coin is tossed 1000 times, if the probability of getting a tail is 3/8, how many times head is obtained?

  • 525

  • 375

  • 625

  •  725

Q 7 | Page 17

A dice is rolled 600 times and the occurrence of the outcomes 1, 2, 3, 4, 5 and 6 are given below:
 

Outcome 1 2 3 4 5 6
Frequency 200 30 120 100 50 100

The probability of getting a prime number is

  • `1/3`

  • `2/3`

  • `49/60`

  • `39/125`

Q 8 | Page 17

The percentage of attendance of different classes in a year in a school is given below:

Class: X IX VIII VII VI V
Attendance: 30 62 85 92 76 55

What is the probability that the class attendance is more than 75%?

  • `1/6`

  • `1/3`

  • `5/6`

  • `1/2`

Q 9 | Page 17

A bag contains 50 coins and each coin is marked from 51 to 100. One coin is picked at random. The probability that the number on the coin is not a prime number, is

  • `1/5`

  • `3/5`

  • `2/5`

  • `4/5`

Q 10 | Page 17

In a football match, Ronaldo makes 4 goals from 10 penalty kicks. The probability of converting a penalty kick into a goal by Ronaldo, is

  • `1/4`

  • `1/6`

  • `1/3`

  • `2/5`

Chapter 25: Probability

Ex. 25.1Others

RD Sharma Mathematics Class 9 by R D Sharma (2018-19 Session)

Mathematics for Class 9 by R D Sharma (2018-19 Session)

RD Sharma solutions for Class 9 Mathematics chapter 25 - Probability

RD Sharma solutions for Class 9 Maths chapter 25 (Probability) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CBSE Mathematics for Class 9 by R D Sharma (2018-19 Session) solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Class 9 Mathematics chapter 25 Probability are Probability - an Experimental Approach.

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