Page 1
1. The probability that it will rain tomorrow is 0.85. What is the probability that it
will not rain tomorrow?
Solution:
Let event of raining tomorrow be P (A)
The probability of raining tomorrow is P (A) = 0.85
Probability of not raining is given by P (A) = 1 – P (A)
? Probability of not raining = P (A) = 1 – 0.85
= 0.15
2. A die thrown. Find the probability of getting:
(i) a prime number
(ii) 2 or 4
(iii) a multiple of 2 or 3
Solution:
(i) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Total number of outcome = 6
Prime numbers are: 1, 3 and 5
Total number of prime numbers = 3
Probability of getting a prime number = Total prime numbers/Total number of outcomes
= 3/6
= 1/2
? Probability of getting a prime number = 1/2
(ii) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Total number of outcome = 6
Probability of getting 2 and 4 is Total numbers/Total number of outcomes
= 2/6
= 1/3
? Probability of getting 2 and 4 is 1/3
(iii) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Multiples of 2 and 3 are = 2, 3, 4 and 6
Total number of multiples are 4
Probability of getting a multiple of 2 or 3 is Total numbers/Total number of outcomes
= 4/6
= 2/3
? Probability of getting a multiple of 2 or 3 is 2/3
Page 2
1. The probability that it will rain tomorrow is 0.85. What is the probability that it
will not rain tomorrow?
Solution:
Let event of raining tomorrow be P (A)
The probability of raining tomorrow is P (A) = 0.85
Probability of not raining is given by P (A) = 1 – P (A)
? Probability of not raining = P (A) = 1 – 0.85
= 0.15
2. A die thrown. Find the probability of getting:
(i) a prime number
(ii) 2 or 4
(iii) a multiple of 2 or 3
Solution:
(i) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Total number of outcome = 6
Prime numbers are: 1, 3 and 5
Total number of prime numbers = 3
Probability of getting a prime number = Total prime numbers/Total number of outcomes
= 3/6
= 1/2
? Probability of getting a prime number = 1/2
(ii) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Total number of outcome = 6
Probability of getting 2 and 4 is Total numbers/Total number of outcomes
= 2/6
= 1/3
? Probability of getting 2 and 4 is 1/3
(iii) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Multiples of 2 and 3 are = 2, 3, 4 and 6
Total number of multiples are 4
Probability of getting a multiple of 2 or 3 is Total numbers/Total number of outcomes
= 4/6
= 2/3
? Probability of getting a multiple of 2 or 3 is 2/3
3. In a simultaneous throw of a pair of dice, find the probability of getting:
(i) 8 as the sum
(ii) a doublet
(iii) a doublet of prime numbers
(iv) a doublet of odd numbers
(v) a sum greater than 9
(vi) An even number on first
(vii) an even number on one and a multiple of 3 on the other
(viii) neither 9 nor 11 as the sum of the numbers on the faces
(ix) a sum less than 6
(x) a sum less than 7
(xi) a sum more than 7
(xii) at least once
(xiii) a number other than 5 on any dice.
Solution:
Let us construct a table.
Here the first number denotes the outcome of first die and second number denotes the
outcome of second die.
(i) 8 as the sum
Total number of outcomes in the above table are 36
Number of outcomes having 8 as sum are: (6, 2), (5, 3), (4, 4), (3, 5) and (2, 6)
Therefore numbers of outcomes having 8 as sum are 5
Probability of getting numbers of outcomes having 8 as sum is = Total numbers/Total
number of outcomes
= 5/36
? Probability of getting numbers of outcomes having 8 as sum is 5/36
Page 3
1. The probability that it will rain tomorrow is 0.85. What is the probability that it
will not rain tomorrow?
Solution:
Let event of raining tomorrow be P (A)
The probability of raining tomorrow is P (A) = 0.85
Probability of not raining is given by P (A) = 1 – P (A)
? Probability of not raining = P (A) = 1 – 0.85
= 0.15
2. A die thrown. Find the probability of getting:
(i) a prime number
(ii) 2 or 4
(iii) a multiple of 2 or 3
Solution:
(i) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Total number of outcome = 6
Prime numbers are: 1, 3 and 5
Total number of prime numbers = 3
Probability of getting a prime number = Total prime numbers/Total number of outcomes
= 3/6
= 1/2
? Probability of getting a prime number = 1/2
(ii) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Total number of outcome = 6
Probability of getting 2 and 4 is Total numbers/Total number of outcomes
= 2/6
= 1/3
? Probability of getting 2 and 4 is 1/3
(iii) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Multiples of 2 and 3 are = 2, 3, 4 and 6
Total number of multiples are 4
Probability of getting a multiple of 2 or 3 is Total numbers/Total number of outcomes
= 4/6
= 2/3
? Probability of getting a multiple of 2 or 3 is 2/3
3. In a simultaneous throw of a pair of dice, find the probability of getting:
(i) 8 as the sum
(ii) a doublet
(iii) a doublet of prime numbers
(iv) a doublet of odd numbers
(v) a sum greater than 9
(vi) An even number on first
(vii) an even number on one and a multiple of 3 on the other
(viii) neither 9 nor 11 as the sum of the numbers on the faces
(ix) a sum less than 6
(x) a sum less than 7
(xi) a sum more than 7
(xii) at least once
(xiii) a number other than 5 on any dice.
Solution:
Let us construct a table.
Here the first number denotes the outcome of first die and second number denotes the
outcome of second die.
(i) 8 as the sum
Total number of outcomes in the above table are 36
Number of outcomes having 8 as sum are: (6, 2), (5, 3), (4, 4), (3, 5) and (2, 6)
Therefore numbers of outcomes having 8 as sum are 5
Probability of getting numbers of outcomes having 8 as sum is = Total numbers/Total
number of outcomes
= 5/36
? Probability of getting numbers of outcomes having 8 as sum is 5/36
(ii) a doublet
Total number of outcomes in the above table are 36
Number of outcomes as doublet are: (1, 1), (2, 2), (3, 3), (4, 4), (5, 5) and (6, 6)
Number of outcomes as doublet are 6
Probability of getting numbers of outcomes as doublet is = Total numbers/Total number
of outcomes
= 6/36
= 1/6
? Probability of getting numbers of outcomes as doublet is 1/6
(iii) a doublet of prime numbers
Total number of outcomes in the above table are 36
Number of outcomes as doublet of prime numbers are: (1, 1), (3, 3), (5, 5)
Number of outcomes as doublet of prime numbers are 3
Probability of getting numbers of outcomes as doublet of prime numbers is = Total
numbers/Total number of outcomes
= 3/36
= 1/12
? Probability of getting numbers of outcomes as doublet of prime numbers is 1/12
(iv) a doublet of odd numbers
Total number of outcomes in the above table are 36
Number of outcomes as doublet of odd numbers are: (1, 1), (3, 3), (5, 5)
Number of outcomes as doublet of odd numbers are 3
Probability of getting numbers of outcomes as doublet of odd numbers is = Total
numbers/Total number of outcomes
= 3/36
= 1/12
? Probability of getting numbers of outcomes as doublet of odd numbers is 1/12
(v) a sum greater than 9
Total number of outcomes in the above table are 36
Number of outcomes having sum greater than 9 are: (4, 6), (5, 5), (5, 6), (6, 6), (6, 4), (6,
5)
Number of outcomes having sum greater than 9 are 6
Probability of getting numbers of outcomes having sum greater than 9 is = Total
numbers/Total number of outcomes
= 6/36 = 1/6
? Probability of getting numbers of outcomes having sum greater than 9 is 1/6
Page 4
1. The probability that it will rain tomorrow is 0.85. What is the probability that it
will not rain tomorrow?
Solution:
Let event of raining tomorrow be P (A)
The probability of raining tomorrow is P (A) = 0.85
Probability of not raining is given by P (A) = 1 – P (A)
? Probability of not raining = P (A) = 1 – 0.85
= 0.15
2. A die thrown. Find the probability of getting:
(i) a prime number
(ii) 2 or 4
(iii) a multiple of 2 or 3
Solution:
(i) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Total number of outcome = 6
Prime numbers are: 1, 3 and 5
Total number of prime numbers = 3
Probability of getting a prime number = Total prime numbers/Total number of outcomes
= 3/6
= 1/2
? Probability of getting a prime number = 1/2
(ii) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Total number of outcome = 6
Probability of getting 2 and 4 is Total numbers/Total number of outcomes
= 2/6
= 1/3
? Probability of getting 2 and 4 is 1/3
(iii) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Multiples of 2 and 3 are = 2, 3, 4 and 6
Total number of multiples are 4
Probability of getting a multiple of 2 or 3 is Total numbers/Total number of outcomes
= 4/6
= 2/3
? Probability of getting a multiple of 2 or 3 is 2/3
3. In a simultaneous throw of a pair of dice, find the probability of getting:
(i) 8 as the sum
(ii) a doublet
(iii) a doublet of prime numbers
(iv) a doublet of odd numbers
(v) a sum greater than 9
(vi) An even number on first
(vii) an even number on one and a multiple of 3 on the other
(viii) neither 9 nor 11 as the sum of the numbers on the faces
(ix) a sum less than 6
(x) a sum less than 7
(xi) a sum more than 7
(xii) at least once
(xiii) a number other than 5 on any dice.
Solution:
Let us construct a table.
Here the first number denotes the outcome of first die and second number denotes the
outcome of second die.
(i) 8 as the sum
Total number of outcomes in the above table are 36
Number of outcomes having 8 as sum are: (6, 2), (5, 3), (4, 4), (3, 5) and (2, 6)
Therefore numbers of outcomes having 8 as sum are 5
Probability of getting numbers of outcomes having 8 as sum is = Total numbers/Total
number of outcomes
= 5/36
? Probability of getting numbers of outcomes having 8 as sum is 5/36
(ii) a doublet
Total number of outcomes in the above table are 36
Number of outcomes as doublet are: (1, 1), (2, 2), (3, 3), (4, 4), (5, 5) and (6, 6)
Number of outcomes as doublet are 6
Probability of getting numbers of outcomes as doublet is = Total numbers/Total number
of outcomes
= 6/36
= 1/6
? Probability of getting numbers of outcomes as doublet is 1/6
(iii) a doublet of prime numbers
Total number of outcomes in the above table are 36
Number of outcomes as doublet of prime numbers are: (1, 1), (3, 3), (5, 5)
Number of outcomes as doublet of prime numbers are 3
Probability of getting numbers of outcomes as doublet of prime numbers is = Total
numbers/Total number of outcomes
= 3/36
= 1/12
? Probability of getting numbers of outcomes as doublet of prime numbers is 1/12
(iv) a doublet of odd numbers
Total number of outcomes in the above table are 36
Number of outcomes as doublet of odd numbers are: (1, 1), (3, 3), (5, 5)
Number of outcomes as doublet of odd numbers are 3
Probability of getting numbers of outcomes as doublet of odd numbers is = Total
numbers/Total number of outcomes
= 3/36
= 1/12
? Probability of getting numbers of outcomes as doublet of odd numbers is 1/12
(v) a sum greater than 9
Total number of outcomes in the above table are 36
Number of outcomes having sum greater than 9 are: (4, 6), (5, 5), (5, 6), (6, 6), (6, 4), (6,
5)
Number of outcomes having sum greater than 9 are 6
Probability of getting numbers of outcomes having sum greater than 9 is = Total
numbers/Total number of outcomes
= 6/36 = 1/6
? Probability of getting numbers of outcomes having sum greater than 9 is 1/6
(vi) An even number on first
Total number of outcomes in the above table are 36
Number of outcomes having an even number on first are: (2, 1), (2, 2), (2, 3), (2, 4), (2,
5), (2, 6), (4, 1), (4, 2), (4, 3), (4, 4), (4, 5), (4, 6), (6, 1), (6, 2), (6, 3), (6, 4), (6, 5) and (6,
6)
Number of outcomes having an even number on first are 18
Probability of getting numbers of outcomes having an even number on first is = Total
numbers/Total number of outcomes
= 18/36
= 1/2
? Probability of getting numbers of outcomes having an even number on first is 1/2
(vii) An even number on one and a multiple of 3 on the other
Total number of outcomes in the above table are 36
Number of outcomes having an even number on one and a multiple of 3 on the other are:
(2, 3), (2, 6), (4, 3), (4, 6), (6, 3) and (6, 6)
Number of outcomes having an even number on one and a multiple of 3 on the other are
6
Probability of getting an even number on one and a multiple of 3 on the other is = Total
numbers/Total number of outcomes
= 6/36
= 1/6
? Probability of getting an even number on one and a multiple of 3 on the other is 1/6
(viii) Neither 9 nor 11 as the sum of the numbers on the faces
Total number of outcomes in the above table are 36
Number of outcomes having 9 nor 11 as the sum of the numbers on the faces are: (3, 6),
(4, 5), (5, 4), (5, 6), (6, 3) and (6, 5)
Number of outcomes having neither 9 nor 11 as the sum of the numbers on the faces are 6
Probability of getting 9 nor 11 as the sum of the numbers on the faces is = Total
numbers/Total number of outcomes
= 6/36
= 1/6
Probability of outcomes having 9 nor 11 as the sum of the numbers on the faces P (E) =
1/6
?Probability of getting neither 9 nor 11 as the sum of the numbers on the faces is 1/6
Probability of outcomes not having 9 nor 11 as the sum of the numbers on the faces is
Page 5
1. The probability that it will rain tomorrow is 0.85. What is the probability that it
will not rain tomorrow?
Solution:
Let event of raining tomorrow be P (A)
The probability of raining tomorrow is P (A) = 0.85
Probability of not raining is given by P (A) = 1 – P (A)
? Probability of not raining = P (A) = 1 – 0.85
= 0.15
2. A die thrown. Find the probability of getting:
(i) a prime number
(ii) 2 or 4
(iii) a multiple of 2 or 3
Solution:
(i) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Total number of outcome = 6
Prime numbers are: 1, 3 and 5
Total number of prime numbers = 3
Probability of getting a prime number = Total prime numbers/Total number of outcomes
= 3/6
= 1/2
? Probability of getting a prime number = 1/2
(ii) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Total number of outcome = 6
Probability of getting 2 and 4 is Total numbers/Total number of outcomes
= 2/6
= 1/3
? Probability of getting 2 and 4 is 1/3
(iii) Outcomes of a die are: 1, 2, 3, 4, 5, 5 and 6
Multiples of 2 and 3 are = 2, 3, 4 and 6
Total number of multiples are 4
Probability of getting a multiple of 2 or 3 is Total numbers/Total number of outcomes
= 4/6
= 2/3
? Probability of getting a multiple of 2 or 3 is 2/3
3. In a simultaneous throw of a pair of dice, find the probability of getting:
(i) 8 as the sum
(ii) a doublet
(iii) a doublet of prime numbers
(iv) a doublet of odd numbers
(v) a sum greater than 9
(vi) An even number on first
(vii) an even number on one and a multiple of 3 on the other
(viii) neither 9 nor 11 as the sum of the numbers on the faces
(ix) a sum less than 6
(x) a sum less than 7
(xi) a sum more than 7
(xii) at least once
(xiii) a number other than 5 on any dice.
Solution:
Let us construct a table.
Here the first number denotes the outcome of first die and second number denotes the
outcome of second die.
(i) 8 as the sum
Total number of outcomes in the above table are 36
Number of outcomes having 8 as sum are: (6, 2), (5, 3), (4, 4), (3, 5) and (2, 6)
Therefore numbers of outcomes having 8 as sum are 5
Probability of getting numbers of outcomes having 8 as sum is = Total numbers/Total
number of outcomes
= 5/36
? Probability of getting numbers of outcomes having 8 as sum is 5/36
(ii) a doublet
Total number of outcomes in the above table are 36
Number of outcomes as doublet are: (1, 1), (2, 2), (3, 3), (4, 4), (5, 5) and (6, 6)
Number of outcomes as doublet are 6
Probability of getting numbers of outcomes as doublet is = Total numbers/Total number
of outcomes
= 6/36
= 1/6
? Probability of getting numbers of outcomes as doublet is 1/6
(iii) a doublet of prime numbers
Total number of outcomes in the above table are 36
Number of outcomes as doublet of prime numbers are: (1, 1), (3, 3), (5, 5)
Number of outcomes as doublet of prime numbers are 3
Probability of getting numbers of outcomes as doublet of prime numbers is = Total
numbers/Total number of outcomes
= 3/36
= 1/12
? Probability of getting numbers of outcomes as doublet of prime numbers is 1/12
(iv) a doublet of odd numbers
Total number of outcomes in the above table are 36
Number of outcomes as doublet of odd numbers are: (1, 1), (3, 3), (5, 5)
Number of outcomes as doublet of odd numbers are 3
Probability of getting numbers of outcomes as doublet of odd numbers is = Total
numbers/Total number of outcomes
= 3/36
= 1/12
? Probability of getting numbers of outcomes as doublet of odd numbers is 1/12
(v) a sum greater than 9
Total number of outcomes in the above table are 36
Number of outcomes having sum greater than 9 are: (4, 6), (5, 5), (5, 6), (6, 6), (6, 4), (6,
5)
Number of outcomes having sum greater than 9 are 6
Probability of getting numbers of outcomes having sum greater than 9 is = Total
numbers/Total number of outcomes
= 6/36 = 1/6
? Probability of getting numbers of outcomes having sum greater than 9 is 1/6
(vi) An even number on first
Total number of outcomes in the above table are 36
Number of outcomes having an even number on first are: (2, 1), (2, 2), (2, 3), (2, 4), (2,
5), (2, 6), (4, 1), (4, 2), (4, 3), (4, 4), (4, 5), (4, 6), (6, 1), (6, 2), (6, 3), (6, 4), (6, 5) and (6,
6)
Number of outcomes having an even number on first are 18
Probability of getting numbers of outcomes having an even number on first is = Total
numbers/Total number of outcomes
= 18/36
= 1/2
? Probability of getting numbers of outcomes having an even number on first is 1/2
(vii) An even number on one and a multiple of 3 on the other
Total number of outcomes in the above table are 36
Number of outcomes having an even number on one and a multiple of 3 on the other are:
(2, 3), (2, 6), (4, 3), (4, 6), (6, 3) and (6, 6)
Number of outcomes having an even number on one and a multiple of 3 on the other are
6
Probability of getting an even number on one and a multiple of 3 on the other is = Total
numbers/Total number of outcomes
= 6/36
= 1/6
? Probability of getting an even number on one and a multiple of 3 on the other is 1/6
(viii) Neither 9 nor 11 as the sum of the numbers on the faces
Total number of outcomes in the above table are 36
Number of outcomes having 9 nor 11 as the sum of the numbers on the faces are: (3, 6),
(4, 5), (5, 4), (5, 6), (6, 3) and (6, 5)
Number of outcomes having neither 9 nor 11 as the sum of the numbers on the faces are 6
Probability of getting 9 nor 11 as the sum of the numbers on the faces is = Total
numbers/Total number of outcomes
= 6/36
= 1/6
Probability of outcomes having 9 nor 11 as the sum of the numbers on the faces P (E) =
1/6
?Probability of getting neither 9 nor 11 as the sum of the numbers on the faces is 1/6
Probability of outcomes not having 9 nor 11 as the sum of the numbers on the faces is
given by P (E) = 1 – 1/6 = (6-1)/5 = 5/6
? Probability of outcomes not having 9 nor 11 as the sum of the numbers on the faces is
5/6
(ix) A sum less than 6
Total number of outcomes in the above table are 36
Number of outcomes having a sum less than 6 are: (1, 1), (1, 2), (1, 3), (1, 4), (2, 1), (2,
2), (2, 3), (3, 1), (3, 2), (4, 1)
Number of outcomes having a sum less than 6 are 10
Probability of getting a sum less than 6 is = Total numbers/Total number of outcomes
= 10/36
= 5/18
? Probability of getting sum less than 6 is 5/18
(x) A sum less than 7
Total number of outcomes in the above table are 36
Number of outcomes having a sum less than 7 are: (1, 1), (1, 2), (1, 3), (1, 4), (1, 5), (2,
1), (2, 2), (2, 3), (2, 4), (3, 1), (3, 2), (3, 3), (4, 1), (4, 2), (5, 1)
Number of outcomes having a sum less than 7 are 15
Probability of getting a sum less than 7 is = Total numbers/Total number of outcomes
= 15/36
= 5/12
? Probability of getting sum less than 7 is 5/12
(xi) A sum more than 7
Total number of outcomes in the above table are 36
Number of outcomes having a sum more than 7 are: (2, 6), (3, 5), (3, 6), (4, 4), (4, 5), (4,
6), (5, 3), (5, 4), (5, 5), (5, 6), (6, 2), (6, 3), (6, 4), (6, 5), (6, 6)
Number of outcomes having a sum more than 7 are 15
Probability of getting a sum more than 7 is = Total numbers/Total number of outcomes
= 15/36
= 5/12
? Probability of getting sum more than 7 is 5/12
(xii) At least once
Total number of outcomes in the above table 1 are 36
Number of outcomes for at least once are 11
Probability of getting outcomes for at least once is = Total numbers/Total number of
outcomes
Read More