NCERT Class 10 Math Chapter 14 Important Questions Answer – Probability

Class 10
Chapter  Probability
Subject Math
Category Important Question Answer

Class 10 Math Chapter 14 Important Question Answer

Q1. 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 perfect square number (ii) a number divisible by 5.

Ans. Total outcomes = 90

(i) Perfect square numbers from 1 to 90 = 9   (1, 4, ….81 )

Probability of getting a perfect square number = \displaystyle \frac{9}{{90}} = \displaystyle \frac{1}{{10}}

(ii) number divisible 5 = 18 (5, 10, .. 90)

Probability of getting a number divisible by 5 = \displaystyle \frac{18}{{90}} = \displaystyle \frac{1}{{5}}

Q2. A lot of 20 bulbs contain 4 defective ones. One bulb is drawn at random from the lot. What is the probability that (i) this bulb is defective ? (ii) this bulb is not defective ?

Ans. Total bulbs = 20, total defective bulbs = 4, total non defective bulbs = 20 – 4 = 16

(i) Probability of getting a defective bulb = \displaystyle \frac{4}{{20}} = \displaystyle \frac{1}{{5}}

(ii) Probability of getting a non defective bulb = 1 – probability of getting a defective bulb

= 1 – \displaystyle \frac{1}{{5}} = \displaystyle \frac{4}{{5}}

Q3. 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. Most Important

Ans. When a die is thrown there are 6 outcomes. Therefore, total outcomes = 6

(i) total prime numbers when a die is thrown = 3  i.e 2, 3, 5

Probability of getting a prime number when a die is thrown = \displaystyle \frac{3}{{6}} = \displaystyle \frac{1}{{2}}

(ii) total numbers lying between 2 and 5 in a die = 3 i.e 3, 4, 5

Probability of getting a number lying between 2 and 6 = \displaystyle \frac{3}{{6}} = \displaystyle \frac{1}{{2}}

(iii) total odd numbers when a die is thrown = 3 i.e 1, 3, 5

Probability of getting an odd number when a die is thrown = \displaystyle \frac{3}{{6}} = \displaystyle \frac{1}{{2}}

Q4. One card is drawn from a well-shuffled deck of 52 cards. Find the probability of getting (i) a king of red colour (ii) a face card. Most Most Important

Ans. Total cards = 52, Total kings of red colour = 2, total face cards = 12

(i) Probability of getting a king of red colour = \displaystyle \frac{2}{{52}} = \displaystyle \frac{1}{{26}}

(ii) Probability of getting a face card = \displaystyle \frac{12}{{52}} = \displaystyle \frac{3}{{13}}

Q5. 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) not red? Most Most Important

Ans. Total balls = 3 + 5 = 8,

Red balls = 3, Black balls = 5

(i) probability of getting a red ball = \displaystyle \frac{3}{{8}}

(ii) Probability of getting a non red ball = 1 – P(red ball)

= 1 – \displaystyle \frac{3}{{8}} = \displaystyle \frac{5}{{8}}

Q6. A die is thrown once, find the probability of getting a prime number.

Ans. Total outcomes = 6, total prime numbers in a die = 3

Probability of getting a prime number when a die is thrown = \displaystyle \frac{3}{{6}} = \displaystyle \frac{1}{{2}}

Q7. The probability of an event that cannot happen is __________ such an event called _______.

Ans. 0, impossible events.

Q8. The probability of an event is greater than or equal to _________ and less than or equal to ________.

Ans. 0, 1

Q9. A die is thrown once. The probability of getting an odd number is __________.

Ans. Total outcomes = 6

Total favorable outcomes i.e total odd numbers = 3

Probability of getting an number when a die is thrown = \displaystyle \frac{3}{{6}} = \displaystyle \frac{1}{{2}}

Q10. If P(E) = 0.25, what is the probability of event ‘not E’.

Ans. P (not E) = 1 – P(E) = 1 – 0.25 = 0.75

Q11. Two dice are thrown at the same time. Find the probability of getting the sum on the dice is 13. Most Important

Ans. As we know that max possible sum when the two dice is thrown is 12.

Therefore, probability of getting the sum on the dice is 13 = 0

Q12. Two dice are thrown at the same time. Find the probability of getting the sum on the dice is less than or equal to 12.

Ans. As we know that max possible sum when the two dice is thrown is 12. It means sum will always be less than or equal to 12.

Therefore, probability of getting the sum on the dice is less than or equal to 12 = 1

Q13. If P(E) = 0.03, what is value of P (not E)?

Ans. P (not E) = 1 – P(E) = 1 – 0.03 = 0.97

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