# RD SHARMA Solutions for Class 9 Maths Chapter 25 - Probability

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## Chapter 25 - Probability Exercise Ex. 25.1

Question 1
A coin is tossed 1000 times with the following frequencies:

Head : 455, Tail : 545

Compute the probability for each event.
Solution 1 Question 2

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.

Solution 2 Question 3 Solution 3 Question 4
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
Solution 4 Question 5
In a cricket match, a batsman hits a boundary 6 times out of 30 balls he plays.

Find the probability that on a ball played:

(i) he hits boundary

(ii) he does not hit a boundary.
Solution 5 Question 6
The percentage of marks obtained by a student in monthly unit tests are given below:

 Units 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.
Solution 6 Question 7 Solution 7 Question 8 Solution 8 Question 9 Solution 9 Question 10

 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.

Solution 10 Question 11 Solution 11 Question 12 Solution 12 Question 13 Solution 13 Question 14 Solution 14 ## Chapter 25 - Probability Exercise 25.16

Question 1

The probability of an impossible event is

(a) 1

(b) 0

(c) less than 0

(d) greater than 1

Solution 1

The probability of an impossible event is always zero since the chances of occurring of that event is zero.

Hence, correct option is (b).

Question 2

The probability of a certain event is

(a) 0

(b) 1

(c) greater than 1

(d) less than 0

Solution 2 Question 3

The probability an event of a trial is

(a) 1

(b) 0

(c) less than 1

(d) more than 1

Solution 3 Question 4 Solution 4 Question 5 Solution 5 ## Chapter 25 - Probability Exercise 25.17

Question 6

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

(a) 525

(b) 375

(c) 625

(d) 725

Solution 6 Question 7

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 Solution 7 Question 8

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%? Solution 8 Question 9

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 Solution 9 Question 10

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 Solution 10 ### STUDY RESOURCES

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