NCERT Solutions, Exercise 15.1: Probability, Class 10 (Mathematics) Class 10 Notes | EduRev

Class 10 : NCERT Solutions, Exercise 15.1: Probability, Class 10 (Mathematics) Class 10 Notes | EduRev

 Page 1


(www.tiwariacademy.net) 
(Class – X) 
 
A Free web support in Education 
 
1 
 
Exercise 15.1 
Question 1:  
Complete the following statements:  
(i) Probability of an event E + Probability of the event ‘not E’ = 
_______.  
(ii) The probability of an event that cannot happen is _________. Such 
as event is called _________.  
(iii) The probability of an event that is certain to happen is _________. 
Such as event is called ________.  
(iv) The sum of the probabilities of all the elementary events of an 
experiment is  
_________.  
(v) The probability of an event is greater than or equal to _______ and 
less than or equal to _______.  
Answer 1:  
(i) 1  
(ii) 0, impossible event  
(iii) 1, sure event or certain event  
(iv) 1  
(v) 0, 1  
Question 2:  
Which of the following experiments have equally likely outcomes? Explain.  
(i) A driver attempts to start a car. The car starts or does not start.  
(ii) A player attempts to shoot a basketball. She/he shoots or misses the 
shot.  
(iii) A trial is made to answer a true-false question. The answer is right or 
wrong.  
(iv) A baby is born. It is a boy or a girl.  
 
Page 2


(www.tiwariacademy.net) 
(Class – X) 
 
A Free web support in Education 
 
1 
 
Exercise 15.1 
Question 1:  
Complete the following statements:  
(i) Probability of an event E + Probability of the event ‘not E’ = 
_______.  
(ii) The probability of an event that cannot happen is _________. Such 
as event is called _________.  
(iii) The probability of an event that is certain to happen is _________. 
Such as event is called ________.  
(iv) The sum of the probabilities of all the elementary events of an 
experiment is  
_________.  
(v) The probability of an event is greater than or equal to _______ and 
less than or equal to _______.  
Answer 1:  
(i) 1  
(ii) 0, impossible event  
(iii) 1, sure event or certain event  
(iv) 1  
(v) 0, 1  
Question 2:  
Which of the following experiments have equally likely outcomes? Explain.  
(i) A driver attempts to start a car. The car starts or does not start.  
(ii) A player attempts to shoot a basketball. She/he shoots or misses the 
shot.  
(iii) A trial is made to answer a true-false question. The answer is right or 
wrong.  
(iv) A baby is born. It is a boy or a girl.  
 
(www.tiwariacademy.net) 
(Class – X) 
 
A Free web support in Education 
 
2 
 
Answer 2:  
(i) It is not an equally likely event, as it depends on various factors such as 
whether the car will start or not. And factors for both the conditions are not 
the same.  
(ii) It is not an equally likely event, as it depends on the player’s ability and 
there is no information given about that.  
(iii) It is an equally likely event.  
(iv) It is an equally likely event.  
 
Question 3:  
Why is tossing a coin considered to be a fair way of deciding which team 
should get the ball at the beginning of a football game?  
Answer 3:  
When we toss a coin, the possible outcomes are only two, head or tail, which 
are equally likely outcomes. Therefore, the result of an individual toss is 
completely unpredictable.  
 
Question 4:  
Which of the following cannot be the probability of an event?  
  
Answer 4:  
Probability of an event (E) is always greater than or equal to 0. Also, it is 
always less than or equal to one. This implies that the probability of an event 
cannot be negative or greater than 1. Therefore, out of these alternatives, 
-1.5 cannot be a probability of an event.  
Hence, (B)  
 
Question 5:  
If P(E) = 0.05, what is the probability of ‘not E’?  
Answer 5:  
We know that,  
Page 3


(www.tiwariacademy.net) 
(Class – X) 
 
A Free web support in Education 
 
1 
 
Exercise 15.1 
Question 1:  
Complete the following statements:  
(i) Probability of an event E + Probability of the event ‘not E’ = 
_______.  
(ii) The probability of an event that cannot happen is _________. Such 
as event is called _________.  
(iii) The probability of an event that is certain to happen is _________. 
Such as event is called ________.  
(iv) The sum of the probabilities of all the elementary events of an 
experiment is  
_________.  
(v) The probability of an event is greater than or equal to _______ and 
less than or equal to _______.  
Answer 1:  
(i) 1  
(ii) 0, impossible event  
(iii) 1, sure event or certain event  
(iv) 1  
(v) 0, 1  
Question 2:  
Which of the following experiments have equally likely outcomes? Explain.  
(i) A driver attempts to start a car. The car starts or does not start.  
(ii) A player attempts to shoot a basketball. She/he shoots or misses the 
shot.  
(iii) A trial is made to answer a true-false question. The answer is right or 
wrong.  
(iv) A baby is born. It is a boy or a girl.  
 
(www.tiwariacademy.net) 
(Class – X) 
 
A Free web support in Education 
 
2 
 
Answer 2:  
(i) It is not an equally likely event, as it depends on various factors such as 
whether the car will start or not. And factors for both the conditions are not 
the same.  
(ii) It is not an equally likely event, as it depends on the player’s ability and 
there is no information given about that.  
(iii) It is an equally likely event.  
(iv) It is an equally likely event.  
 
Question 3:  
Why is tossing a coin considered to be a fair way of deciding which team 
should get the ball at the beginning of a football game?  
Answer 3:  
When we toss a coin, the possible outcomes are only two, head or tail, which 
are equally likely outcomes. Therefore, the result of an individual toss is 
completely unpredictable.  
 
Question 4:  
Which of the following cannot be the probability of an event?  
  
Answer 4:  
Probability of an event (E) is always greater than or equal to 0. Also, it is 
always less than or equal to one. This implies that the probability of an event 
cannot be negative or greater than 1. Therefore, out of these alternatives, 
-1.5 cannot be a probability of an event.  
Hence, (B)  
 
Question 5:  
If P(E) = 0.05, what is the probability of ‘not E’?  
Answer 5:  
We know that,  
(www.tiwariacademy.net) 
(Class – X) 
A Free web support in Education 
3 
Therefore, the probability of ‘not E’ is 0.95.  
Question 6:  
A bag contains lemon flavoured candies only. Malini takes out one candy 
without looking into the bag. What is the probability that she takes out  
(i) an orange flavoured candy?  
(ii) a lemon flavoured candy?  
Answer 6:  
(i) The bag contains lemon flavoured candies only. It does not contain any 
orange flavoured candies. This implies that every time, she will take out 
only lemon flavoured candies. Therefore, event that Malini will take out an 
orange flavoured candy is an impossible event.  
Hence, P (an orange flavoured candy) = 0  
(ii) As the bag has lemon flavoured candies, Malini will take out only lemon 
flavoured candies. Therefore, event that Malini will take out a lemon 
flavoured candy is a sure event.  
P (a lemon flavoured candy) = 1  
Question 7:  
It is given that in a group of 3 students, the probability of 2 students not 
having the same birthday is 0.992. What is the probability that the 2 students 
have the same birthday?  
Answer 7:  
Probability that two students are not having same birthday P ( ) = 0.992  
Page 4


(www.tiwariacademy.net) 
(Class – X) 
 
A Free web support in Education 
 
1 
 
Exercise 15.1 
Question 1:  
Complete the following statements:  
(i) Probability of an event E + Probability of the event ‘not E’ = 
_______.  
(ii) The probability of an event that cannot happen is _________. Such 
as event is called _________.  
(iii) The probability of an event that is certain to happen is _________. 
Such as event is called ________.  
(iv) The sum of the probabilities of all the elementary events of an 
experiment is  
_________.  
(v) The probability of an event is greater than or equal to _______ and 
less than or equal to _______.  
Answer 1:  
(i) 1  
(ii) 0, impossible event  
(iii) 1, sure event or certain event  
(iv) 1  
(v) 0, 1  
Question 2:  
Which of the following experiments have equally likely outcomes? Explain.  
(i) A driver attempts to start a car. The car starts or does not start.  
(ii) A player attempts to shoot a basketball. She/he shoots or misses the 
shot.  
(iii) A trial is made to answer a true-false question. The answer is right or 
wrong.  
(iv) A baby is born. It is a boy or a girl.  
 
(www.tiwariacademy.net) 
(Class – X) 
 
A Free web support in Education 
 
2 
 
Answer 2:  
(i) It is not an equally likely event, as it depends on various factors such as 
whether the car will start or not. And factors for both the conditions are not 
the same.  
(ii) It is not an equally likely event, as it depends on the player’s ability and 
there is no information given about that.  
(iii) It is an equally likely event.  
(iv) It is an equally likely event.  
 
Question 3:  
Why is tossing a coin considered to be a fair way of deciding which team 
should get the ball at the beginning of a football game?  
Answer 3:  
When we toss a coin, the possible outcomes are only two, head or tail, which 
are equally likely outcomes. Therefore, the result of an individual toss is 
completely unpredictable.  
 
Question 4:  
Which of the following cannot be the probability of an event?  
  
Answer 4:  
Probability of an event (E) is always greater than or equal to 0. Also, it is 
always less than or equal to one. This implies that the probability of an event 
cannot be negative or greater than 1. Therefore, out of these alternatives, 
-1.5 cannot be a probability of an event.  
Hence, (B)  
 
Question 5:  
If P(E) = 0.05, what is the probability of ‘not E’?  
Answer 5:  
We know that,  
(www.tiwariacademy.net) 
(Class – X) 
A Free web support in Education 
3 
Therefore, the probability of ‘not E’ is 0.95.  
Question 6:  
A bag contains lemon flavoured candies only. Malini takes out one candy 
without looking into the bag. What is the probability that she takes out  
(i) an orange flavoured candy?  
(ii) a lemon flavoured candy?  
Answer 6:  
(i) The bag contains lemon flavoured candies only. It does not contain any 
orange flavoured candies. This implies that every time, she will take out 
only lemon flavoured candies. Therefore, event that Malini will take out an 
orange flavoured candy is an impossible event.  
Hence, P (an orange flavoured candy) = 0  
(ii) As the bag has lemon flavoured candies, Malini will take out only lemon 
flavoured candies. Therefore, event that Malini will take out a lemon 
flavoured candy is a sure event.  
P (a lemon flavoured candy) = 1  
Question 7:  
It is given that in a group of 3 students, the probability of 2 students not 
having the same birthday is 0.992. What is the probability that the 2 students 
have the same birthday?  
Answer 7:  
Probability that two students are not having same birthday P ( ) = 0.992  
(www.tiwariacademy.net) 
(Class – X) 
 
A Free web support in Education 
 
4 
 
Probability that two students are having same birthday P (E) = 1 - P ( )  
= 1 - 0.992  
= 0.008  
 
Question 8:  
A bag contains 3 red balls and 5 black balls. A ball is drawn at random from 
the bag.  
What is the probability that the ball drawn is (i) red? (ii) not red?  
Answer 8:  
(i) Total number of balls in the bag = 8  
  
(ii) Probability of not getting red ball  
= 1 - Probability of getting a red ball  
  
 
Question 9:  
A box contains 5 red marbles, 8 white marbles and 4 green marbles. One 
marble is taken out of the box at random. What is the probability that the 
marble taken out will be (i) red? (ii) white? (iii) not green?  
Answer 9:  
Total number of marbles = 5 + 8 + 4  
= 17  
(i) Number of red marbles = 5  
Page 5


(www.tiwariacademy.net) 
(Class – X) 
 
A Free web support in Education 
 
1 
 
Exercise 15.1 
Question 1:  
Complete the following statements:  
(i) Probability of an event E + Probability of the event ‘not E’ = 
_______.  
(ii) The probability of an event that cannot happen is _________. Such 
as event is called _________.  
(iii) The probability of an event that is certain to happen is _________. 
Such as event is called ________.  
(iv) The sum of the probabilities of all the elementary events of an 
experiment is  
_________.  
(v) The probability of an event is greater than or equal to _______ and 
less than or equal to _______.  
Answer 1:  
(i) 1  
(ii) 0, impossible event  
(iii) 1, sure event or certain event  
(iv) 1  
(v) 0, 1  
Question 2:  
Which of the following experiments have equally likely outcomes? Explain.  
(i) A driver attempts to start a car. The car starts or does not start.  
(ii) A player attempts to shoot a basketball. She/he shoots or misses the 
shot.  
(iii) A trial is made to answer a true-false question. The answer is right or 
wrong.  
(iv) A baby is born. It is a boy or a girl.  
 
(www.tiwariacademy.net) 
(Class – X) 
 
A Free web support in Education 
 
2 
 
Answer 2:  
(i) It is not an equally likely event, as it depends on various factors such as 
whether the car will start or not. And factors for both the conditions are not 
the same.  
(ii) It is not an equally likely event, as it depends on the player’s ability and 
there is no information given about that.  
(iii) It is an equally likely event.  
(iv) It is an equally likely event.  
 
Question 3:  
Why is tossing a coin considered to be a fair way of deciding which team 
should get the ball at the beginning of a football game?  
Answer 3:  
When we toss a coin, the possible outcomes are only two, head or tail, which 
are equally likely outcomes. Therefore, the result of an individual toss is 
completely unpredictable.  
 
Question 4:  
Which of the following cannot be the probability of an event?  
  
Answer 4:  
Probability of an event (E) is always greater than or equal to 0. Also, it is 
always less than or equal to one. This implies that the probability of an event 
cannot be negative or greater than 1. Therefore, out of these alternatives, 
-1.5 cannot be a probability of an event.  
Hence, (B)  
 
Question 5:  
If P(E) = 0.05, what is the probability of ‘not E’?  
Answer 5:  
We know that,  
(www.tiwariacademy.net) 
(Class – X) 
A Free web support in Education 
3 
Therefore, the probability of ‘not E’ is 0.95.  
Question 6:  
A bag contains lemon flavoured candies only. Malini takes out one candy 
without looking into the bag. What is the probability that she takes out  
(i) an orange flavoured candy?  
(ii) a lemon flavoured candy?  
Answer 6:  
(i) The bag contains lemon flavoured candies only. It does not contain any 
orange flavoured candies. This implies that every time, she will take out 
only lemon flavoured candies. Therefore, event that Malini will take out an 
orange flavoured candy is an impossible event.  
Hence, P (an orange flavoured candy) = 0  
(ii) As the bag has lemon flavoured candies, Malini will take out only lemon 
flavoured candies. Therefore, event that Malini will take out a lemon 
flavoured candy is a sure event.  
P (a lemon flavoured candy) = 1  
Question 7:  
It is given that in a group of 3 students, the probability of 2 students not 
having the same birthday is 0.992. What is the probability that the 2 students 
have the same birthday?  
Answer 7:  
Probability that two students are not having same birthday P ( ) = 0.992  
(www.tiwariacademy.net) 
(Class – X) 
 
A Free web support in Education 
 
4 
 
Probability that two students are having same birthday P (E) = 1 - P ( )  
= 1 - 0.992  
= 0.008  
 
Question 8:  
A bag contains 3 red balls and 5 black balls. A ball is drawn at random from 
the bag.  
What is the probability that the ball drawn is (i) red? (ii) not red?  
Answer 8:  
(i) Total number of balls in the bag = 8  
  
(ii) Probability of not getting red ball  
= 1 - Probability of getting a red ball  
  
 
Question 9:  
A box contains 5 red marbles, 8 white marbles and 4 green marbles. One 
marble is taken out of the box at random. What is the probability that the 
marble taken out will be (i) red? (ii) white? (iii) not green?  
Answer 9:  
Total number of marbles = 5 + 8 + 4  
= 17  
(i) Number of red marbles = 5  
(www.tiwariacademy.net) 
(Class – X) 
 
A Free web support in Education 
 
5 
 
  
 
(ii) Number of white marbles = 8  
  
 
(iii) Number of green marbles = 4  
  
  
Question 10:  
A piggy bank contains hundred 50 p coins, fifty Rs 1 coins, twenty Rs 2 
coins and ten Rs 5 coins. If it is equally likely that one of the coins will fall 
out when the bank is turned upside down, what is the probability that the 
coin  
(i) Will be a 50 p coin?   
(ii) Will not be a Rs.5 coin?  
Answer 10:  
Total number of coins in a piggy bank = 100 + 50 + 20 + 10 = 180  
Probability of not getting a green marble  
  
Read More
Offer running on EduRev: Apply code STAYHOME200 to get INR 200 off on our premium plan EduRev Infinity!

Related Searches

NCERT Solutions

,

past year papers

,

Objective type Questions

,

Free

,

NCERT Solutions

,

ppt

,

Viva Questions

,

study material

,

Class 10 (Mathematics) Class 10 Notes | EduRev

,

NCERT Solutions

,

shortcuts and tricks

,

Important questions

,

Sample Paper

,

Previous Year Questions with Solutions

,

Exercise 15.1: Probability

,

Extra Questions

,

MCQs

,

pdf

,

Class 10 (Mathematics) Class 10 Notes | EduRev

,

Exam

,

video lectures

,

Exercise 15.1: Probability

,

Summary

,

Class 10 (Mathematics) Class 10 Notes | EduRev

,

Semester Notes

,

Exercise 15.1: Probability

,

practice quizzes

,

mock tests for examination

;