RS Aggarwal MCQs: Probability Notes | EduRev

Mathematics (Maths) Class 9

Class 9 : RS Aggarwal MCQs: Probability Notes | EduRev

 Page 1


     
             
              
             ?  ?     
              
                   
Q u e s t i o n : 1 9
In a sample survey of 645 people, it was found that 516 people have a high school certificate. If a person is chosen
at random, what is the probability that he / she has a high school certificate?
a
1
2
b
3
5
c
7
10
d
4
5
S o l u t i o n :
Total number of people surveyed = 645
Number of people who have a high school certificate = 516
? PPersonhasahighschoolcertificate
= 
Number of people who have a high school certificate
Total number of people surveyed
=
516
645
=
4
5
Hence, the correct answer is option d
.
Q u e s t i o n : 2 0
In a medical examination of students of a class, the following blood groups are recorded:
Blood group A B AB O
Number of students 11 15 8 6
From this class, a student is chosen at random. What is the probability that the chosen student has blood group
AB?
a
Page 2


     
             
              
             ?  ?     
              
                   
Q u e s t i o n : 1 9
In a sample survey of 645 people, it was found that 516 people have a high school certificate. If a person is chosen
at random, what is the probability that he / she has a high school certificate?
a
1
2
b
3
5
c
7
10
d
4
5
S o l u t i o n :
Total number of people surveyed = 645
Number of people who have a high school certificate = 516
? PPersonhasahighschoolcertificate
= 
Number of people who have a high school certificate
Total number of people surveyed
=
516
645
=
4
5
Hence, the correct answer is option d
.
Q u e s t i o n : 2 0
In a medical examination of students of a class, the following blood groups are recorded:
Blood group A B AB O
Number of students 11 15 8 6
From this class, a student is chosen at random. What is the probability that the chosen student has blood group
AB?
a
b
c
d
S o l u t i o n :
c
Explanation:
Total number of students = 40
 Number of students with blood group AB = 8
 Let E be the event that the selected student's blood group is AB. 
 
   ? Required probability = P(E) =  
8
40
 = 
1
5
Q u e s t i o n : 2 1
80 bulbs are selected at random from a lot and their lifetime is hours is recorded as under.
Lifetime 
inhours
300 500 700 900 1100
Frequency 10 12 23 25 10
One bulb is selected at random from the lot. What is the probability that its life is 1150?
a
1
80
b
7
16
c
1
d
0
S o l u t i o n :
d
0
Maximum lifetime a bulb has is 1100 hours. There is no bulb with lifetime 1150 hours.
Q u e s t i o n : 2 2
In a survey of 364 children aged 19 – 36 months, it was found that 91 liked to eat potato chips. If a child is selected
at random, the probability that he / she does not like to eat potato chips is
13
20
3
8
1
5
11
40
1
5
 = 0. 35
Page 3


     
             
              
             ?  ?     
              
                   
Q u e s t i o n : 1 9
In a sample survey of 645 people, it was found that 516 people have a high school certificate. If a person is chosen
at random, what is the probability that he / she has a high school certificate?
a
1
2
b
3
5
c
7
10
d
4
5
S o l u t i o n :
Total number of people surveyed = 645
Number of people who have a high school certificate = 516
? PPersonhasahighschoolcertificate
= 
Number of people who have a high school certificate
Total number of people surveyed
=
516
645
=
4
5
Hence, the correct answer is option d
.
Q u e s t i o n : 2 0
In a medical examination of students of a class, the following blood groups are recorded:
Blood group A B AB O
Number of students 11 15 8 6
From this class, a student is chosen at random. What is the probability that the chosen student has blood group
AB?
a
b
c
d
S o l u t i o n :
c
Explanation:
Total number of students = 40
 Number of students with blood group AB = 8
 Let E be the event that the selected student's blood group is AB. 
 
   ? Required probability = P(E) =  
8
40
 = 
1
5
Q u e s t i o n : 2 1
80 bulbs are selected at random from a lot and their lifetime is hours is recorded as under.
Lifetime 
inhours
300 500 700 900 1100
Frequency 10 12 23 25 10
One bulb is selected at random from the lot. What is the probability that its life is 1150?
a
1
80
b
7
16
c
1
d
0
S o l u t i o n :
d
0
Maximum lifetime a bulb has is 1100 hours. There is no bulb with lifetime 1150 hours.
Q u e s t i o n : 2 2
In a survey of 364 children aged 19 – 36 months, it was found that 91 liked to eat potato chips. If a child is selected
at random, the probability that he / she does not like to eat potato chips is
13
20
3
8
1
5
11
40
1
5
 = 0. 35
a
1
4
b
1
2
c
3
4
d
4
5
S o l u t i o n :
Total number of children surveyed = 364
Number of children who liked to eat potato chips = 91
Number of children who do not liked to eat potato chips = 364 - 91 = 273
? PChilddoesnotliketoeatpotatochips
= 
Number of children who do not liked to eat potato chips
Total number of children surveyed
=
273
364
=
3
4
Hence, the correct answer is option c
.
Q u e s t i o n : 2 3
Two coins are tossed 1000 times and the outcomes are recorded as given below:
Number of
heads
2 1 0
Frequency 200 550 250
Now, if two coins are tossed at random, what is the probability of getting at most one head?
a
3
4
b
4
5
c
1
4
d
1
5
S o l u t i o n :
Page 4


     
             
              
             ?  ?     
              
                   
Q u e s t i o n : 1 9
In a sample survey of 645 people, it was found that 516 people have a high school certificate. If a person is chosen
at random, what is the probability that he / she has a high school certificate?
a
1
2
b
3
5
c
7
10
d
4
5
S o l u t i o n :
Total number of people surveyed = 645
Number of people who have a high school certificate = 516
? PPersonhasahighschoolcertificate
= 
Number of people who have a high school certificate
Total number of people surveyed
=
516
645
=
4
5
Hence, the correct answer is option d
.
Q u e s t i o n : 2 0
In a medical examination of students of a class, the following blood groups are recorded:
Blood group A B AB O
Number of students 11 15 8 6
From this class, a student is chosen at random. What is the probability that the chosen student has blood group
AB?
a
b
c
d
S o l u t i o n :
c
Explanation:
Total number of students = 40
 Number of students with blood group AB = 8
 Let E be the event that the selected student's blood group is AB. 
 
   ? Required probability = P(E) =  
8
40
 = 
1
5
Q u e s t i o n : 2 1
80 bulbs are selected at random from a lot and their lifetime is hours is recorded as under.
Lifetime 
inhours
300 500 700 900 1100
Frequency 10 12 23 25 10
One bulb is selected at random from the lot. What is the probability that its life is 1150?
a
1
80
b
7
16
c
1
d
0
S o l u t i o n :
d
0
Maximum lifetime a bulb has is 1100 hours. There is no bulb with lifetime 1150 hours.
Q u e s t i o n : 2 2
In a survey of 364 children aged 19 – 36 months, it was found that 91 liked to eat potato chips. If a child is selected
at random, the probability that he / she does not like to eat potato chips is
13
20
3
8
1
5
11
40
1
5
 = 0. 35
a
1
4
b
1
2
c
3
4
d
4
5
S o l u t i o n :
Total number of children surveyed = 364
Number of children who liked to eat potato chips = 91
Number of children who do not liked to eat potato chips = 364 - 91 = 273
? PChilddoesnotliketoeatpotatochips
= 
Number of children who do not liked to eat potato chips
Total number of children surveyed
=
273
364
=
3
4
Hence, the correct answer is option c
.
Q u e s t i o n : 2 3
Two coins are tossed 1000 times and the outcomes are recorded as given below:
Number of
heads
2 1 0
Frequency 200 550 250
Now, if two coins are tossed at random, what is the probability of getting at most one head?
a
3
4
b
4
5
c
1
4
d
1
5
S o l u t i o n :
Total number of times two coins are tossed = 1000
Number of times of getting at most one head = Number of times of getting 0 heads + Number of times of getting 1
head = 250 + 550 = 800
? PGettingatmostonehead
= 
Number of times of getting at most one head
Total number of times two coins are tossed
=
800
1000
=
4
5
Hence, the correct answer is option b
.
Q u e s t i o n : 2 4
80 bulbs are selected at random from a lot and their lifetime in hours is recorded as under.
Lifetime inhours 300 500 700 900 1100
Frequency 10 12 23 25 10
One bulb is selected at random from the lot. What is the probability that the selected bulb has a life more than 500
hours?
a
b
c
d
S o l u t i o n :
b
Explanation:
 Total number of bulbs in the lot  = 80
 Number of bulbs with life time of more than 500 hours =
23 +25 +10 = 58
 Let E be the event that the chosen bulb's life time is more than 500 hours. 
 
? Required probability = P(E) =  
58
80
 = 
29
40
Q u e s t i o n : 2 5
To know the opinion of the students about the subject Sanskrit, a survey of 200 students was conducted. The data
is recorded as under.
Opinion like dislike
27
40
29
40
5
16
11
40
29
40
Page 5


     
             
              
             ?  ?     
              
                   
Q u e s t i o n : 1 9
In a sample survey of 645 people, it was found that 516 people have a high school certificate. If a person is chosen
at random, what is the probability that he / she has a high school certificate?
a
1
2
b
3
5
c
7
10
d
4
5
S o l u t i o n :
Total number of people surveyed = 645
Number of people who have a high school certificate = 516
? PPersonhasahighschoolcertificate
= 
Number of people who have a high school certificate
Total number of people surveyed
=
516
645
=
4
5
Hence, the correct answer is option d
.
Q u e s t i o n : 2 0
In a medical examination of students of a class, the following blood groups are recorded:
Blood group A B AB O
Number of students 11 15 8 6
From this class, a student is chosen at random. What is the probability that the chosen student has blood group
AB?
a
b
c
d
S o l u t i o n :
c
Explanation:
Total number of students = 40
 Number of students with blood group AB = 8
 Let E be the event that the selected student's blood group is AB. 
 
   ? Required probability = P(E) =  
8
40
 = 
1
5
Q u e s t i o n : 2 1
80 bulbs are selected at random from a lot and their lifetime is hours is recorded as under.
Lifetime 
inhours
300 500 700 900 1100
Frequency 10 12 23 25 10
One bulb is selected at random from the lot. What is the probability that its life is 1150?
a
1
80
b
7
16
c
1
d
0
S o l u t i o n :
d
0
Maximum lifetime a bulb has is 1100 hours. There is no bulb with lifetime 1150 hours.
Q u e s t i o n : 2 2
In a survey of 364 children aged 19 – 36 months, it was found that 91 liked to eat potato chips. If a child is selected
at random, the probability that he / she does not like to eat potato chips is
13
20
3
8
1
5
11
40
1
5
 = 0. 35
a
1
4
b
1
2
c
3
4
d
4
5
S o l u t i o n :
Total number of children surveyed = 364
Number of children who liked to eat potato chips = 91
Number of children who do not liked to eat potato chips = 364 - 91 = 273
? PChilddoesnotliketoeatpotatochips
= 
Number of children who do not liked to eat potato chips
Total number of children surveyed
=
273
364
=
3
4
Hence, the correct answer is option c
.
Q u e s t i o n : 2 3
Two coins are tossed 1000 times and the outcomes are recorded as given below:
Number of
heads
2 1 0
Frequency 200 550 250
Now, if two coins are tossed at random, what is the probability of getting at most one head?
a
3
4
b
4
5
c
1
4
d
1
5
S o l u t i o n :
Total number of times two coins are tossed = 1000
Number of times of getting at most one head = Number of times of getting 0 heads + Number of times of getting 1
head = 250 + 550 = 800
? PGettingatmostonehead
= 
Number of times of getting at most one head
Total number of times two coins are tossed
=
800
1000
=
4
5
Hence, the correct answer is option b
.
Q u e s t i o n : 2 4
80 bulbs are selected at random from a lot and their lifetime in hours is recorded as under.
Lifetime inhours 300 500 700 900 1100
Frequency 10 12 23 25 10
One bulb is selected at random from the lot. What is the probability that the selected bulb has a life more than 500
hours?
a
b
c
d
S o l u t i o n :
b
Explanation:
 Total number of bulbs in the lot  = 80
 Number of bulbs with life time of more than 500 hours =
23 +25 +10 = 58
 Let E be the event that the chosen bulb's life time is more than 500 hours. 
 
? Required probability = P(E) =  
58
80
 = 
29
40
Q u e s t i o n : 2 5
To know the opinion of the students about the subject Sanskrit, a survey of 200 students was conducted. The data
is recorded as under.
Opinion like dislike
27
40
29
40
5
16
11
40
29
40
Number of
students
135 65
What is the probability that a student chosen at random does not like it?
a
13
27
b
27
40
c
13
40
d
27
13
S o l u t i o n :
Total number of students surveyed = 200
Number of students who does not like the subject Sanskrit = 65
? PStudentchosenatrandomdoesnotlikethesubjectSanskrit
= 
Number of students who does not like the subject Sanskrit
Total number of students surveyed
=
65
200
=
13
40
Hence, the correct answer is option c
.
Q u e s t i o n : 2 6
A coin is tossed 60 times and the tail appears 35 times. What is the probability of getting a head?
a
7
12
b
12
7
c
5
12
d
1
25
S o l u t i o n :
c
 
5
12
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