CBSE Board Practice

Class VI Class VII Class VIII Class IX Class X
CBSE Grade IX - Probability
Question 1
1.
Two coins are tossed simultaneously 60 times and it was observed that both tails appeared 30 times. If two coins are tossed simultaneously at random, what is the probability of getting both tails?
  • 2
    3
  • 3
    4
  • 5
    6
  • 4
    5
  • 1
    2
Question 2
2.
In a lottery, there are 22 prizes and 16 blanks. What is the probability of getting a prize?
  • 3
    5
  • 11
    19
  • 10
    19
  • 12
    19
  • 8
    19
Question 3
3.
    • 279 families with 2 children were selected randomly, and the following data were recorded
    • No. of girls in a family
      0
      1
      2
      Number of families
      72
      99
      108
    • Compute the probability of the family, chosen at random, having 1 girl.
  • 20
    31
  • 12
    31
  • 11
    31
  • 3
    8
  • 10
    31
Question 4
4.
    • The following table shows the blood-groups of 423 students of a class.
    • Blood group
      A
      O
      B
      AB
      Number of students
      45
      99
      126
      153
    • One student of the class is choosen at random. What is the probability that the choosen student has blood group 'B' ?
  • 5
    16
  • 14
    47
  • 15
    47
  • 33
    47
  • 13
    47
Question 5
5.
Which of the following experiments have equally likely outcomes?
a)
A ball is hit. It reaches the boundary or not
b)
A baby is born. It is a boy or girl
c)
A man starts his vehicle. It starts or it does not starts
d)
A true/false question is attempted. The answer is either right or wrong
e)
A man throws a die. The number on the top is either 4 or not 4
  • {b,d}
  • {c,d}
  • {a,b}
  • {c,d,b}
  • {e,a,b}
Question 6
6.
A die is thrown 400 times. The number 3 appears on the upper face 80 times. Now the die is thrown at random. What is the probability of getting a 3 ?
  • 0
  • 2
    5
  • 1
    5
  • 1
    3
  • 4
    5
Question 7
7.
Which of the following are true?
a)
    • P(E) - P(
    •  

      E
       
       
    • ) = 0
b)
    • P(E) = 1 - P(
    •  

      E
       
       
    • )
c)
    • P(E) + P(
    •  

      E
       
       
    • ) = 0
d)
    • P(E) + P(not E) = 1
e)
    • P(E) - P(not E) = 0
  • {a,b}
  • {b,d}
  • {c,d}
  • {c,d,b}
  • {e,a,b}
Question 8
8.
There are 56 students in a class room of whom 30 are boys and 26 are girls. From these students, one is choosen at random. What is the probability that the choosen student is a boy ?
  • 4
    7
  • 13
    28
  • 16
    29
  • 1
    2
  • 15
    28
Question 9
9.
    • Three coins are tossed simultaneously 150 times with the following frequencies of different outcomes :
    • Outcome
      3 heads
      2 heads
      1 heads
      No heads
      Frequency
      30
      35
      40
      45
    • If the three coins are simultaneously tossed again, compute the probability of '1 heads' coming up.
  • 4
    15
  • 5
    16
  • 11
    15
  • 1
    5
  • 1
    3
Question 10
10.
A coin is tossed 60 times and head appears 35 times. If the coin is tossed again, what is the probability of getting a tail?
  • 5
    12
  • 6
    13
  • 7
    12
  • 1
    2
  • 1
    3