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NCERT Class 10 Mathematics Chapter 14 Probability
Also, you can read the CBSE book online in these sections Solutions by Expert Teachers as per (CBSE) Book guidelines. NCERT Class 10 Mathematics Textual Question Answer. These solutions are part of NCERT All Subject Solutions. Here we have given NCERT Class 10 Mathematics Chapter 14 Probability Solutions for All Subject, You can practice these here.
Probability
Chapter – 14
| Exercise 14.1 |
1. Complete the following statements:
(i) Probability of an event E + Probability of the event ‘not E’ = _____________.
Ans: 1
(ii) The probability of an event that cannot happen is ____________ such as event is called ______________.
Ans: 0, impossible event.
(iii) The probability of an event that is certain to happen is _____________ such as event is called _____________.
Ans: 1, sure event or certain event.
(iv) The sum of the probabilities of all the elementary events of an experiment is ______________.
Ans: 1
(v) The probability of an event is greater than or equal to ____________ and less than or equal to _____________.
Ans: 0, 1
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.
Ans: 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) A player attempts to shoot a basketball. She/he shoots or misses the Shot.
Ans: It is not an equally likely event, as it depends on the player’s ability and there is no information given about that.
(iii) A trial is made to answer a true-false question. The answer is right or Wrong.
Ans: It is an equally likely event.
(iv) A baby is born. It is a boy or a girl.
Ans: It is an equally likely event.
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?
Ans: 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.
4. Which of the following cannot be the probability of an event?
(a) ⅔
(b) – 1.5
(c) 15%
(d) 0.7
Ans: 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)
5. If P(E) = 0.05, what is the probability of ‘not E’?
Ans: We know that
Therefore, the probability of ‘not E’ is 0.95.
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?
Ans: 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) a lemon flavoured candy?
Ans: 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
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?
Ans: Probability that two students are not having same birthday P (E ) = 0.992
Probability that two students are having same birthday P (E) = 1 − P (E)
= 1 − 0.992
= 0.008
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?
Ans: Total number getting a red ball = Number of favourable outcomes/ Number of total possible outcomes.
= 3 / 8
(ii) Not red?
Ans: Probability of not getting red ball
= 1 − Probability of getting a red ball
= 1-⅜
= ⅝
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?
Ans: Total number of marbles = 5 + 8 + 4 = 17
Number of red marbles = 5
Probability of getting = Number of favourable outcomes = 5/17
(ii) white?
Ans: Number of white marbles = 8
Probability of getting while marble = Number of favourable outcomes / Number of total possible outcomes.
(iii) not green?
Ans: Probability of getting green marble = 1-4/17 = 13/17
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?
Ans: Total number of coins in a piggy bank = 100 + 50 + 20 + 10 = 180
Probability of getting 50 P coin = Number of favourable outcomes / Number of total possible outcomes
= 100/ 180
= 5/9
(ii) Will not be a Rs.5 coin?
Ans: Probability of getting 50 P coin = Number of favourable outcomes / Number of total possible outcomes
= 10/180
1/3
Probability of not getting a Rs 5 coin = 1- ⅛
= 17/18
11. Gopi buys fish from a shop for his aquarium. The shopkeeper takes out one fish at random from a tank containing 5 male fish and 8 female fish (see the given figure). What is the probability that the fish taken out is a male fish?
Ans: Total number of fishes in a tank = Number of male fishes + Number of female fishes = 5 /13
12. A game of chance consists of spinning an arrow which comes to rest pointing at one of the numbers 1, 2, 3, 4, 5, 6, 7, 8 (see the given figure), and these are equally likely outcomes. What is the probability that it will point at:
(i) 8?
Ans: Probability of getting 8 = Number of favourable outcomes / Number of total possible outcomes = ½
(ii) An odd number?
Ans: Total number of odd numbers on spinner = 4 Number of favourable outcomes / Number of total possible outcomes = 4/8 = 1/2
(iii) A number greater than 2?
Ans: The numbers greater than 2 are 3, 4, 5, 6, 7, and 8. Therefore, total
numbers greater than 2 = 6
Probability of getting a number greater than 2
= Number of favourable outcomes / Number of possible of outcomes = 6/8 = ¾
(iv) A number less than 9?
Ans: The numbers less than 9 are 1, 2, 3, 4, 6, 7, and 8.
Therefore, total numbers less than 9 = 8
Probability of getting a number less than 9 = 8/8 =- 1
13. A die is thrown once. Find the probability of getting:
(i) A prime number.
(ii) a number lying between 2 and 6.
(iii) an odd number.
Ans: The possible outcomes when a dice is thrown = {1, 2, 3, 4, 5, 6}
Number of possible outcomes of a dice = 6
(i) Prime numbers on a dice are 2, 3, and 5
Total prime numbers on a dice = 3
(ii) Probability of getting a prime number = 3 , 4 , 5
Total number lying between 2 and 6 = 3
Probability of getting a number = 3/6 = 1/
(iii) Odd numbers on a dice = 1, 3, and 5
Total odd numbers on a dice = 3
Probability of getting an odd number = 3/6 = ½
14. One card is drawn from a well-shuffled deck of 52 cards. Find the
probability of getting.
Total number of cards in a well-shuffled deck = 52
(i) A king of red colour.
Ans: Total of numbers of king of red colour = 2
P (getting a king of red colour) = number of favourable outcomes/Number of total possible outcomes = 12/52 = 3/26
(ii) A face card.
Ans: Total number of face cards = 12
P (getting a face card) = Number of favourable outcomes/ Number of total possible outcomes = 12/52 = 3/13
(iii) A red face card.
Ans: Total number of red face cards = 6
P (getting a red face cards = Number of favourable outcomes/ Number of total possible outcomes = 6/52 = 3/26
(iv) The jack of hearts.
Ans: Total number of Jack of hearts = 1
P (getting a Jack of hearts) = Number of favourable outcomes / Number of total possible = 1/52
(v) A spade.
Ans: Total number of spade cards = 13
(vi) The queen of diamonds.
Ans: P (getting a spade card) = Number of favourable outcomes / Number of total possible = 1/52
15. Five cards−−the ten, jack, queen, king and ace of diamonds, are well shuffled with their face downwards. One card is then picked up at random.
(i) What is the probability that the card is the queen?
Ans: Total number of cards = 5
Total number of queens = 1
P (getting a queen) = Number of favourable outcomes / Number of total possible = 1/5
(ii) If the queen is drawn and put aside, what is the probability that the.
Ans: When the queen is drawn and put aside, the total number of remaining cards will be 4.
Total number of odd numbers on spinner = 4
(a) Total number of aces = 1
P (getting an ace) = ¼
(b) As queen is already drawn, therefore, the number of queens will be 0.
P (getting a queen) = 0
16. 12 defective pens are accidentally mixed with 132 good ones. It is not possible to just look at a pen and tell whether or not it is defective. One pen is taken out at random from this lot. Determine the probability that the pen taken out is a good one.
Ans: Total number of pens = 12 + 132 = 144
Total number of good pens = 132
P (getting a good pen) = Number of favourable / Number of total possible outcomes = 132/144 = 11/12
17. (i) A lot of 20 bulbs contain 4 defective ones. One bulb is drawn at random from the lot. What is the probability that this bulb is defective?
Ans: Total number of bulbs = 20
Total number of defective bulbs = 4
P (getting a defective bulb) = Number of favourable / Number of total possible outcomes = 4/20 = 1/5
(ii) Suppose the bulb drawn in (i) is not defective and is not replaced.
Now one bulb is drawn at random from the rest. What is the probability that this bulb not defective?
Ans: Remaining total number of bulbs = 19
Remaining total number of non-defective bulbs = 16 − 1 = 15
P (getting a not defective bulb) = 15/19
18. A box contains 90 discs which are numbered from 1 to 90. If one disc is
drawn at random from the box, find the probability that it bears.
(i) a two-digit number.
Ans: Total number of discs = 90
(i) Total number of two-digit numbers between 1 and 90 = 81
P (getting a two-digit number) = 81/90 = 9/10
(ii) a perfect square number.
Ans: Perfect squares between 1 and 90 are 1, 4, 9, 16, 25, 36, 49, 64, and 81.
Therefore, total number of perfect squares between 1 and 90 is 9.
P (getting a perfect square) = 9/90 = 1/10
(iii) a number divisible by 5.
Ans: Numbers that are between 1 and 90 and divisible by 5 are 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, and 90. Therefore, total numbers divisible by 5 = 18
Probability of getting a number divisible by 5 = 18/90 = 1/5
19. A child has a die whose six faces shows the letters as given below:
The die is thrown once. What is the probability of getting (i) A? (ii) D?
Ans: Total number of possible outcomes on the dice = 6
Total number of faces having A on it = 2
P (getting A) = 2/ 6 = ⅓
(ii) Total number of faces having D on it = 1
P (getting D) = ⅙
20. Suppose you drop a die at random on the rectangular region shown in the given figure. What is the probability that it will land inside the circle with diameter 1 m?
Ans: Area of rectangle = l × b = 3 × 2 = 6 m2
Area of circle (of diameter 1 m) = 𝜋𝑟2 = 𝜋 (1/2)2= 𝜋/4
P (die will land inside the circle) = 𝜋/4/6 = 𝜋/24
21. A lot consists of 144 ball pens of which 20 are defective and the others are good. Nuri will buy a pen if it is good, but will not buy it if it is defective. The shopkeeper draws one pen at random and gives it to her. What is the probability that.
(i) She will buy it?
(ii) She will not buy it?
Ans: Total number of pens = 144
Total number of defective pens = 20
Total number of good pens = 144 − 20 = 124
(i) Probability of getting a good pen = 124/144 = 31/36
P (Nuri buys a pen) = 31/36
(ii) P (Nuri will not buy a pen) = 1 = 31/36 = 5/ 36
22. Two dice, one blue and one grey, are thrown at the same time.
(i) Write down all the possible outcomes and complete the following table:
| Event: Sum of two dice | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Probability | 1/36 | 5/36 | 1/36 |
Ans:
| Event: Sum of two dice | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Probability | 1/36 | 2/36 | 3/36 | 4/36 | 5/36 | 6/36 | 5/36 | 4/36 | 3/36 | 2/36 | 1/36 |
Ans: It can be observed that,
To get the sum as 2, possible outcomes = (1, 1)
To get the sum as 3, possible outcomes = (2, 1) and (1, 2)
To get the sum as 4, possible outcomes = (3, 1), (1, 3), (2, 2)
To get the sum as 5, possible outcomes = (4, 1), (1, 4), (2, 3), (3, 2)
To get the sum as 6, possible outcomes = (5, 1), (1, 5), (2, 4), (4, 2), (3, 3)
To get the sum as 7, possible outcomes = (6, 1), (1, 6), (2, 5), (5, 2), (3, 4), (4, 3)
To get the sum as 8, possible outcomes = (6, 2), (2, 6), (3, 5), (5, 3), (4, 4)
To get the sum as 9, possible outcomes = (3, 6), (6, 3), (4, 5), (5, 4)
To get the sum as 10, possible outcomes = (4, 6), (6, 4), (5, 5)
To get the sum as 11, possible outcomes = (5, 6), (6, 5)
To get the sum as 12, possible outcomes = (6, 6)
(ii) Probability of each of these sums will not be as these sums are not equally likely
23. A game consists of tossing a one rupee coin 3 times and noting its outcome each time. Hanif wins if all the tosses give the same result i.e., three heads or three tails, and loses otherwise. Calculate the probability that Hanif will lose the game.
Ans: The possible outcomes are
{HHH, TTT, HHT, HTH, THH, TTH, THT, HTT}
Number of total possible outcomes = 8
Number of favourable outcomes = 2 {i.e., TTT and HHH}
P (Hanif will win the game) = 2/8 = ¼
P ( Hanif will lose the games ) = 1 = ¼ = 3/ 4
24. A die is thrown twice. What is the probability that:
(i) 5 will not come up either time?
(ii) 5 will come up at least once?
Ans: Total number of outcomes = 6 × 6 = 36
(i) Total number of outcomes when 5 comes up on either time are (5, 1), (5,2), (5, 3), (5, 4), (5, 5), (5, 6), (1, 5), (2, 5), (3, 5), (4, 5), (6, 5)
Hence, total number of favourable cases = 11 /36
P (5 will not come up either time) = 1 = 11/36 = 25/36
25. Which of the following arguments are correct and which are not correct? Give reasons for your answer.
(i) If two coins are tossed simultaneously there are three possible outcomes−−two heads, two tails or one of each. Therefore, for each of these outcomes, the probability is 1/3.
Ans: Incorrect
When two coins are tossed, the possible outcomes are (H, H), (H, T), (T,H), and (T, T). It can be observed that there can be one of each in two possible ways − (H, T), (T, H).
Therefore, the probability of getting two heads is 1/4, the probability of getting two tails is 1/4, and the probability of getting one of each is 1/2.
It can be observed that for each outcome, the probability is not 1/3
(ii) If a die is thrown, there are two possible outcomes−−an odd number or an even number. Therefore, the probability of getting an odd number is 1/2.
Ans: Correct
When a dice is thrown, the possible outcomes are 1, 2, 3, 4, 5, and 6. Out of these, 1, 3, 5 are odd and 2, 4, 6 are even numbers.
Therefore, the probability of getting an odd number is 1/2.