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# RD Sharma solutions for Mathematics for Class 9 chapter 25 - Probability [Latest edition]

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## Chapter 25: Probability

Ex. 25.1Others

### RD Sharma solutions for Mathematics for Class 9 Chapter 25 Probability 25.1 [Pages 13 - 15]

Ex. 25.1 | Q 1 | Page 13

A coin is tossed 1000 times with the following frequencies:
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:
One tail: 290 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:

If the three coins are simultaneously tossed again, compute the probability of:
(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 70007000-1000010000-1300013000-1600016000 or more 100121 160305535469579 2527292982 0212588

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.

### RD Sharma solutions for Mathematics for Class 9 Chapter 25 Probability [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:

Find the probability of getting at most two heads.

Q 8 | Page 16

what is the probability of getting at least two heads?

### RD Sharma solutions for Mathematics for Class 9 Chapter 25 Probability [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

Ex. 25.1Others

## RD Sharma solutions for Mathematics for Class 9 chapter 25 - Probability

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

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