The word probability is commonly used in our day-to-day conversation, like it may probably rain today, he is probably right, he may probably join games etc. However, in the theory of probability, we assign a numerical value to the degree of uncertainty. ‘Probability’ has emerged as one of the basic tools of statistics today and has a wide range of applications in science and engineering. We will see all these applications in Chapter 26. For quick reference, students can refer to RD Sharma Solutions. The solutions of this exercise are available in the RD Sharma Solutions Class 8 Maths Chapter 26 Exercise 26.1 in PDF, which is provided in the links below.
Chapter 26 Data Handling – IV (Probability) contains one exercise, and the RD Sharma Class 8 Solutions available on this page provide solutions to the questions present in this exercise. Now, let us have a look at the concepts discussed in this chapter.
- A theoretical approach to probability
- Elementary event
- Compound event
- The occurrence of an event
- Favourable elementary events
- The negation of an event
- Theoretical probability
RD Sharma Solutions for Class 8 Maths Chapter 26 Data Handling – IV (Probability)
Access Answers to RD Sharma Solutions for Class 8 Maths Chapter 26 Data Handling – IV (Probability)
EXERCISE 26.1 PAGE NO: 26.14
1. The probability that it will rain tomorrow is 0.85. What is the probability that it will not rain tomorrow?
Solution:
Let the event of raining tomorrow be P (A)
The probability of raining tomorrow is P (A) = 0.85
The 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 is 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 outcomes = 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 outcomes = 6
The probability of getting 2 and 4 is Total numbers/Total number of outcomes
= 2/6
= 1/3
∴ The 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
The total number of multiples is 4
The probability of getting a multiple of 2 or 3 is Total numbers/Total number of outcomes
= 4/6
= 2/3
∴ The 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 is 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 the first die, and the second number denotes the outcome of the second die.
(i) 8 as the sum
The total number of outcomes in the above table is 36
The number of outcomes having 8 as the sum is: (6, 2), (5, 3), (4, 4), (3, 5) and (2, 6)
Therefore the number of outcomes having 8 as the sum is 5
Probability of getting the number of outcomes having 8 as the sum is = Total numbers/Total number of outcomes
= 5/36
∴ Probability of getting the number of outcomes having 8 as the sum is 5/36.
(ii) A doublet
The total number of outcomes in the above table is 36
The number of outcomes as doublet are: (1, 1), (2, 2), (3, 3), (4, 4), (5, 5) and (6, 6)
The number of outcomes as doublet is 6
Probability of getting the number of outcomes as doublet is = Total numbers/Total number of outcomes
= 6/36
= 1/6
∴ Probability of getting the number of outcomes as doublet is 1/6.
(iii) A doublet of prime numbers
The total number of outcomes in the above table is 36
The number of outcomes as a doublet of prime numbers are: (1, 1), (3, 3), (5, 5)
The number of outcomes as a doublet of prime numbers is 3
Probability of getting numbers of outcomes as a doublet of prime numbers is = Total numbers/Total number of outcomes
= 3/36
= 1/12
∴ Probability of getting numbers of outcomes as a doublet of prime numbers is 1/12.
(iv) A doublet of odd numbers
The total number of outcomes in the above table is 36
The number of outcomes as a doublet of odd numbers are: (1, 1), (3, 3), (5, 5)
The number of outcomes as a doublet of odd numbers is 3
Probability of getting numbers of outcomes as a doublet of odd numbers is = Total numbers/Total number of outcomes
= 3/36
= 1/12
∴ Probability of getting numbers of outcomes as a doublet of odd numbers is 1/12.
(v) A sum greater than 9
The total number of outcomes in the above table is 36
The number of outcomes having a sum greater than 9 is: (4, 6), (5, 5), (5, 6), (6, 6), (6, 4), (6, 5)
The number of outcomes having a sum greater than 9 is 6
The probability of getting the number of outcomes having a sum greater than 9 is = Total numbers/Total number of outcomes
= 6/36 = 1/6
∴ The probability of getting numbers of outcomes having a sum greater than 9 is 1/6.
(vi) An even number on first
The total number of outcomes in the above table is 36
The number of outcomes having an even number on first is: (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)
The number of outcomes having an even number on the first is 18
The probability of getting numbers of outcomes having an even number on first is = Total numbers/Total number of outcomes
= 18/36
= 1/2
∴ The 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
The total number of outcomes in the above table is 36
The number of outcomes having an even number on one and a multiple of 3 on the other is: (2, 3), (2, 6), (4, 3), (4, 6), (6, 3) and (6, 6)
The number of outcomes having an even number on one and a multiple of 3 on the other is 6
The 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
∴ The probability of getting an even number on one and a multiple of 3 on the other is 1/6.
(viii) Neither 9 nor 11 is the sum of the numbers on the faces
The total number of outcomes in the above table is 36
The number of outcomes having 9 nor 11 as the sum of the numbers on the faces is: (3, 6), (4, 5), (5, 4), (5, 6), (6, 3) and (6, 5)
The number of outcomes having neither 9 nor 11 as the sum of the numbers on the faces is 6
Probability of getting 9 or 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
The 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
∴ The 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
The total number of outcomes in the above table is 36
The number of outcomes having a sum less than 6 is: (1, 1), (1, 2), (1, 3), (1, 4), (2, 1), (2, 2), (2, 3), (3, 1), (3, 2), (4, 1)
The number of outcomes having a sum less than 6 is 10
The probability of getting a sum less than 6 is = Total numbers/Total number of outcomes
= 10/36
= 5/18
∴ The probability of getting a sum less than 6 is 5/18.
(x) A sum less than 7
The total number of outcomes in the above table is 36
The number of outcomes having a sum less than 7 is: (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)
The number of outcomes having a sum less than 7 is 15
The probability of getting a sum less than 7 is = Total numbers/Total number of outcomes
= 15/36
= 5/12
∴ The probability of getting a sum less than 7 is 5/12.
(xi) A sum more than 7
The total number of outcomes in the above table is 36
The number of outcomes having a sum more than 7 is: (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)
The number of outcomes having a sum more than 7 is 15
The probability of getting a sum more than 7 is = Total numbers/Total number of outcomes
= 15/36
= 5/12
∴ The probability of getting a sum more than 7 is 5/12.
(xii) At least once
The total number of outcomes in the above table 1 is 36
The number of outcomes for at least once is 11
The probability of getting outcomes at least once is = Total numbers/Total number of outcomes
= 11/36
∴ The probability of getting outcomes at least once is 11/36.
(xiii) A number other than 5 on any dice.
The total number of outcomes in the above table 1 is 36
The number of outcomes having 5 on any die is: (1, 5), (2, 5), (3, 5), (4, 5), (5, 1), (5, 2), (5, 3), (5, 4), (5, 5), (5, 6), (6, 5)
The number of outcomes having 5 on any die is 15
The probability of getting 5 on any die is = Total numbers/Total number of outcomes
= 11/36
∴ The probability of getting 5 on any die is 11/36
Probability of not getting 5 on any die P (E) = 1 – P (E)
= 1 – 11/36
= (36-11)/36
= 25/36
4. Three coins are tossed together. Find the probability of getting:
(i) exactly two heads
(ii) at least two heads
(iii) at least one head and one tail
(iv) no tails
Solution:
(i) Exactly two heads
The possible outcome of tossing three coins are: HTT, HHT, HHH, HTH, TTT, TTH, THT, THH
The number of outcomes of exactly two heads is: 3
The probability of getting exactly two heads is = Total numbers/Total number of outcomes
= 3/8
∴ The probability of getting exactly two heads is 3/8.
(ii) At least two heads
The possible outcome of tossing three coins are: HTT, HHT, HHH, HTH, TTT, TTH, THT, THH
The number of outcomes of at least two heads is: 4
The probability of getting at least two heads is = Total numbers/Total number of outcomes
= 4/8
= 1/2
∴ The probability of getting at least two heads is 1/2
(iii) At least one head and one tail
The possible outcome of tossing three coins are: HTT, HHT, HHH, HTH, TTT, TTH, THT, THH
The number of outcomes of at least one head and one tail is: 6
The probability of getting at least one head and one tail is = Total numbers/Total number of outcomes
= 6/8
= 3/4
∴ The probability of getting at least one head and one tail is 3/4.
(iv) No tails
The possible outcome of tossing three coins are: HTT, HHT, HHH, HTH, TTT, TTH, THT, THH
The number of outcomes of no tails is: 1
The probability of getting no tails is = Total numbers/Total number of outcomes
= 1/8
∴ The probability of getting no tails is 1/8.
5. A card is drawn at random from a pack of 52 cards. Find the probability that the card drawn is:
(i) a black king
(ii) either a black card or a king
(iii) black and a king
(iv) a jack, queen or a king
(v) neither a heart nor a king
(vi) spade or an ace
(vii) neither an ace nor a king
(viii) neither a red card nor a queen
(ix) other than an ace
(x) a ten
(xi) a spade
(xii) a black card
(xiii) the seven of clubs
(xiv) jack
(xv) the ace of spades
(xvi) a queen
(xvii) a heart
(xviii) a red card
Solution:
(i) A black king
The total number of cards is 52
Number of black king cards = 2
The probability of getting black king cards is = Total number of black king cards/Total number of cards
= 2/52
= 1/26
∴ The probability of getting black king cards is 1/26.
(ii) Either a black card or a king
The total number of cards is 52
Number of either a black card or a king = 28
The probability of getting either a black card or a king is = Total number of either black or king card/Total number of cards
= 28/52
= 7/13
∴ The probability of getting either a black card or a king is 7/13.
(iii) Black and a king
The total number of cards is 52
Number of black and a king = 2
The probability of getting black and a king is = Total number of black and king cards/Total number of cards
= 2/52
= 1/26
∴ The probability of getting black and a king is 1/26.
(iv) a jack, queen or a king
The total number of cards is 52
The number of a jack, queen or king = 12
The probability of getting a jack, queen or king is = Total number of jack, queen or king cards/Total number of cards
= 12/52
= 3/13
∴ The probability of getting a jack, queen or king is 3/13.
(v) Neither a heart nor a king
The total numbers of cards are 52
Total number of heart cards = 13
The probability of getting a heart is = Total number of hearts/Total number of cards
= 13/52
= 1/4
Total number of king cards = 4
Probability of getting a king is = Total number of king cards/Total number of cards
= 4/52
= 1/13
Total probability of getting a heart and a king = 13/52 + 4/52 – 1/52
= (13+4-1)/52
= 16/52
= 4/13
∴ Probability of getting neither a heart nor a king = 1 – 4/13 = (13-4)/13 = 9/13.
(vi) Spade or an ace
The total numbers of cards are 52
Number of spade cards = 13
The probability of getting spade cards is = Total number of spade cards/Total number of cards
= 13/52
Number of ace cards = 4
The probability of getting ace cards is = Total number of ace cards/Total number of cards
= 4/52
= 1/13
The probability of getting ace and spade cards is = Total number of ace and spade cards/Total number of cards
= 1/52
The probability of getting an ace or spade card is = 13/52 + 4/52 – 1/52
= (13+4-1)/52
= 16/52
= 4/13
∴ The probability of getting an ace or spade card is = 4/13.
(vii) Neither an ace nor a king
The total numbers of cards are 52
Number of king cards = 4
Number of ace cards = 4
Total number of cards = 4 + 4 = 8
The total number of neither an ace nor a king is = 52 – 8 = 44
The probability of getting neither an ace nor a king is = Total number of neither an ace nor king card/Total number of cards
= 44/52
= 11/13
∴ The probability of getting neither an ace nor a king is 11/13.
(viii) Neither a red card nor a queen
The total numbers of cards are 52
Red cards include hearts and diamonds
Number of hearts in a deck of 52 cards = 13
Number of diamonds in a deck of 52 cards = 13
Number of queens in a deck of 52 cards = 4
Total number of red card and queen = 13 + 13 + 2 = 28 [since the queen of heart and queen of diamond are removed]
Number of cards which is neither a red card nor a queen = 52 – 28 = 24
The probability of getting neither a king nor a queen is = Total number of neither red nor queen cards/Total number of cards
= 24/52
= 6/13
∴ The probability of getting neither a king nor a queen is 6/13.
(ix) Other than an ace
The total numbers of cards are 52
Total number of ace cards = 4
Total number of non-ace cards = 52-4 = 48
The probability of getting non-ace is = Total number of non-ace cards/Total number of cards
= 48/52
= 12/13
∴ The probability of getting a non-ace card is 12/13.
(x) A ten
The total numbers of cards are 52
Total number of ten cards = 4
The probability of getting ten cards is = Total number of ten cards/Total number of cards
= 4/52
= 1/13
∴ The probability of getting ten cards is 1/13.
(xi) A spade
The total numbers of cards are 52
Total number of spade cards = 13
The probability of getting a spade is = Total number of spade cards/Total number of cards
= 13/52
= 1/4
∴ The probability of getting a spade is 1/4.
(xii) A black card
The total numbers of cards are 52
Cards of spades and clubs are black cards.
Number of spades = 13
Number of clubs = 13
Total number of black cards out of 52 cards = 13 + 13 = 26
The probability of getting black cards is = Total number of black cards/Total number of cards
= 26/52
= 1/2
∴ The probability of getting a black card is 1/2.
(xiii) The seven of clubs
The total numbers of cards are 52
Total number of the seven of clubs cards = 1
The probability of getting the seven of clubs cards is = Total number of the seven of club cards/ Total number of cards
= 1/52
∴ The probability of the seven of club cards is 1/52.
(xiv) Jack
The total numbers of cards are 52
Total number of jack cards = 4
The probability of getting jack cards is = Total number of jack cards/ Total number of cards
= 4/52
= 1/13
∴ The probability of the jack card is 1/13.
(xv) The ace of spades
The total numbers of cards are 52
Total number of the ace of spades cards = 1
The probability of getting an ace of spade cards is = Total number of the ace of spade cards/ Total number of cards
= 1/52
∴ The probability of an ace of spade card is 1/52.
(xvi) A queen
The total numbers of cards are 52
Total number of queen cards = 4
The probability of getting queen cards is = Total number of queen cards/Total number of cards
= 4/52
= 1/13
∴ The probability of a queen card is 1/13.
(xvii) A heart
The total numbers of cards are 52
Total number of heart cards = 13
The probability of getting queen cards is = Total number of heart cards/Total number of cards
= 13/52
= 1/4
∴ The probability of a heart card is 1/4.
(xviii) A red card
The total numbers of cards are 52
Total number of red cards = 13+13 = 26
The probability of getting queen cards is = Total number of red cards/Total number of cards
= 26/52
= 1/2
∴ The probability of a red card is 1/2.
6. An urn contains 10 red and 8 white balls. One ball is drawn at random. Find the probability that the ball drawn is white.
Solution:
Total number of red balls = 10
Total number of red white balls = 8
Total number of balls = 10 + 8 = 18
The probability of getting a white ball is = Total number of white balls/Total number of balls
= 8/18
= 4/9
∴ The probability of a white ball is 4/9.
7. A bag contains 3 red balls, 5 black balls and 4 white balls. A ball is drawn at random from the bag. What is the probability that the ball drawn is:
(i) white?
(ii) red?
(iii) black?
(iv) not red?
Solution:
(i) White?
Total numbers of red balls = 3
Number of black balls = 5
Number of white balls = 4
Total number of balls = 3 + 5 + 4 = 12
The probability of getting a white ball is = Total number of white balls/Total number of balls
= 4/12
= 1/3
∴ The probability of a white ball is 1/3.
(ii) red?
Total numbers of red balls = 3
Number of black balls = 5
Number of white balls = 4
Total number of balls = 3 + 5 + 4 = 12
The probability of getting a red ball is = Total number of red balls/Total number of balls
= 3/12
= 1/4
∴ The probability of a red ball is 1/4.
(iii) black?
Total numbers of red balls = 3
Number of black balls = 5
Number of white balls = 4
Total number of balls = 3 + 5 + 4 = 12
The probability of getting a black ball is = Total number of black balls/Total number of balls
= 5/12
∴ The probability of a black ball is 5/12.
(iv) not red?
Total numbers of red balls = 3
Number of black balls = 5
Number of white balls = 4
Total number of Non red balls = 5 + 4 = 9
The probability of getting a not red ball is = Total number of not red balls/Total number of balls
= 9/12
= 3/4
∴ The probability of not getting a red ball is 3/4.
8. What is the probability that a number selected from the numbers 1, 2, 3, …, 15 is a multiple of 4?
Solution:
The total numbers are 15
Multiples of 4 are = 4, 8, 12
The probability of getting a multiple of 4 is = Total number of multiples of 4/Total numbers
= 3/15
= 1/5
∴ The probability of getting multiples of 4 is 1/5.
9. A bag contains 6 red, 8 black and 4 white balls. A ball is drawn at random. What is the probability that the ball drawn is not black?
Solution:
Total numbers of red balls = 6
Number of black balls = 8
Number of white balls = 4
Total number of non-red balls = 6 + 8 + 4 = 18
Number of non-black balls are = 6 + 4 = 10
The probability of getting a non-black ball is = Total number of non-black balls/Total number of balls
= 10/18
= 5/9
∴ The probability of getting a non-black ball is 5/9.
10. A bag contains 5 white and 7 red balls. One ball is drawn at random. What is the probability that the ball drawn is white?
Solution:
Total numbers of red balls = 7
Number of white balls = 5
Total number of Non red balls = 7 + 5 = 12
The probability of getting a non-white ball is = Total number of non-white balls/Total number of balls
= 5/12
∴ The probability of getting a non-white ball is 5/12.
11. A bag contains 4 red, 5 black and 6 white balls. One ball is drawn from the bag at random. Find the probability that the ball drawn is:
(i) white
(ii) red
(iii) not black
(iv) red or white
Solution:
(i) White
Total numbers of red balls = 4
Number of black balls = 5
Number of white balls = 6
Total number of balls = 4 + 5 + 6 = 15
The probability of getting a white ball is = Total number of white balls/Total number of balls
= 6/15
= 2/5
∴ The probability of getting a white ball is 2/5.
(ii) Red
Total numbers of red balls = 4
Number of black balls = 5
Number of white balls = 6
Total number of balls = 4 + 5 + 6 = 15
The probability of getting a red ball is = Total number of red balls/Total number of balls
= 4/15
∴ The probability of getting a white ball is 4/15.
(iii) Not black
Total numbers of red balls = 4
Number of black balls = 5
Number of white balls = 6
Total number of balls = 4 + 5 + 6 = 15
Number of non-black balls = 4 + 6 = 10
The probability of getting a non-black ball is = Total number of non-black balls/Total number of balls
= 10/15
= 2/3
∴ The probability of getting a non-black ball is 2/3.
(iv) Red or white
Total numbers of red balls = 4
Number of black balls = 5
Number of white balls = 6
Total number of balls = 4 + 5 + 6 = 15
Number of red and white balls = 4 + 6 = 10
The probability of getting a red or white ball is = Total number of red or white balls/Total number of balls
= 10/15
= 2/3
∴ The probability of getting a red or white ball is 2/3.
12. 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) black
Solution:
(i) Red
Total numbers of red balls = 3
Number of black balls = 5
Total number of balls = 3 + 5 = 8
The probability of getting a red ball is = Total number of red balls/Total number of balls
= 3/8
∴ The probability of getting a red ball is 3/8.
(ii) Black
Total numbers of red balls = 3
Number of black balls = 5
Total number of balls = 3 + 5 = 8
The probability of getting a black ball is = Total number of black balls/Total number of balls
= 5/8
∴ The probability of getting a black ball is 5/8.
13. A bag contains 5 red marbles, 8 white marbles and 4 green marbles. What is the probability that if one marble is taken out of the bag at random, it will be
(i) red
(ii) white
(iii) not green
Solution:
(i) Red
Total number of red marbles = 5
Number of white marbles = 8
Number of green marbles = 4
Total number of marbles = 5 + 8 + 4 = 17
The probability of getting a red marble is = Total number of red marbles/Total number of marbles
= 5/17
∴ The probability of getting a red marble is 5/17.
(ii) White
Total number of red marbles = 5
Number of white marbles = 8
Number of green marbles = 4
Total number of marbles = 5 + 8 + 4 = 17
The probability of getting a white marble is = Total number of white marbles/Total number of marbles
= 8/17
∴ The probability of getting a white marble is 8/17.
(iii) Not green
Total number of red marbles = 5
Number of white marbles = 8
Number of green marbles = 4
Total number of marbles = 5 + 8 + 4 = 17
Total number of non-green marbles = 5 + 8 = 13
The probability of getting a non-green marble is = Total number of non-green marbles/Total number of marbles
= 13/17
∴ The probability of getting a non-green marble is 13/17.
14. If you put 21 consonants and 5 vowels in a bag. What would carry greater probability? Getting a consonant or a vowel? Find each probability.
Solution:
Total numbers of consonants = 21
Number of white vowels = 5
Total number of alphabets = 21 + 5 = 26
The probability of getting a consonant is = Total number of consonants/Total number of alphabets
= 21/26
The probability of getting a vowel is = Total number of vowels/Total number of alphabets
= 5/26
∴ The probability of getting a consonant is more.
15. If we have 15 boys and 5 girls in a class which carries a higher probability? Getting a copy belonging to a boy or a girl. Can you give it a value?
Solution:
Total number of boys in a class = 15
Number of girls in a class = 5
Total number of students = 15 + 5 = 20
The probability of getting a copy of a boy is = Total number of boys/Total number of students
= 15/20
= 3/4
The probability of getting a copy of a girl is = Total number of girls/Total number of students
= 5/20
= 1/4
∴ The probability of getting a copy of a boy is more.
16. If you have a collection of 6 pairs of white socks and 3 pairs of black socks. What is the probability that a pair you pick without looking is (i) white? (ii) black?
Solution:
Total number of white socks = 6 pairs
Total number of black socks = 3 pairs
Total number pairs of socks = 6 + 3 = 9
(i) Probability of getting a white sock is = Total number of white socks/Total number of socks
= 6/9
= 2/3
∴ The probability of white socks is 2/3.
(ii) Probability of getting a black sock is = Total number of black socks/Total number of socks
= 3/9
= 1/3
∴ The probability of black socks is 1/3.
17. If you have a spinning wheel with 3 green sectors, 1 blue sector and 1 red sector, what is the probability of getting a green sector? Is it the maximum?
Solution:
Total number of green sectors = 3
Total numbers of blue sector = 1
Total numbers of red sector = 1
Total number of sectors = 3 + 1 + 1 = 5
The probability of getting a green sector is = Total number of green sectors/Total number of sectors
= 3/5
The probability of getting a blue sector is = Total number of blue sectors/Total number of sectors
= 1/5
The probability of getting a red sector is = Total number of red sectors/Total number of sectors
= 1/5
Yes, the probability of getting a green sector is maximum.
18. When two dice are rolled:
(i) List the outcomes for the event that the total is odd.
(ii) Find the probability of getting an odd total.
(iii) List the outcomes for the event that the total is less than 5.
(iv) Find the probability of getting a total less than 5.
Solution:
(i) List the outcomes for the event that the total is odd.
Possible outcomes of two dice are:
Outcomes for the event that the total is odd are: (2, 1), (4, 1), (6, 1), (1, 2), (3, 2), (5, 2), (2, 3), (4, 3), (6, 3), (1, 4), (3, 4), (5, 4), (2, 5), (4, 5), (6, 5), (1, 6), (3, 6), (5, 6)
(ii) Find the probability of getting an odd total.
The total number of outcomes from two dice is 36
From the above table, we get that the total number of outcomes for the event of getting an odd total is 18.
Probability of getting an event that the total is odd = Total number of events with odd total/Total number of events
= 18/36
= 1/2
∴ The probability of getting an odd total is 1/2.
(iii) List the outcomes for the event that the total is less than 5.
The total numbers of outcomes from two dice are 36
The total number of outcomes of the events that total is less than 5 are: (1, 1), (2, 1), (3, 1), (1, 2), (2, 2) and (1, 3)
(iv) Find the probability of getting a total less than 5.
The total numbers of outcomes from two dice are 36
The total number of events that total is less than 5 are: (1, 1), (2, 1), (3, 1), (1, 2), (2, 2) and (1, 3)
Probability of getting an event that total is less than 5 = Total number of events with a total less than 5 /Total number of events
= 6/36
= 1/6
∴ The probability of getting an event that the total is less than 5 is 1/6.
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