RS Aggarwal - Mathematics

Book: RS Aggarwal - Mathematics

Chapter: 24. Probability

Subject: Maths - Class 8th

Q. No. 10 of Exercise 24A

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10

A box contains 19 balls bearing numbers 1, 2, 3 ..., 19 respectively. A ball is drawn at random from the box. Find the probability that the number on the ball is (i) a prime number (ii) an even number (iii) a number divisible by 3.

(i) Total number of ball bearings = 19


Chances of drawing a prime numbered ball = 9 (They are 2,3,5,7,11,13,17,19)


Probability P() =


Probability of drawing a prime numbered ball bearing P(prime ball)


= =


(ii) Total number of ball bearings = 19


Chances of drawing an even numbered ball = 9 (They are 2,4,6,8,10,12,14,16,18)


Probability P() =


Probability of drawing an even numbered ball bearing P(even ball)


= =


(iii) Total number of ball bearings = 19


Chances of drawing a numbered ball which is divisible by 3 =6 (They are 3,6,9,12,15,18)


Probability P() =


Probability of drawing a numbered ball bearing which is divisible by 3 P(ball divisible by 3)


= =


Chapter Exercises

Exercise 24A
Exercise 24B

More Exercise Questions

1

A coin is tossed. What are all possible outcomes?

(i) Two coins are tossed simultaneously. What are all possible outcomes?


(ii) A die is thrown. What are all possible outcomes?


(iii) From a well-shuffled deck of 52 cards, one card is drawn at random. What is the number of all possible outcomes?
2

In a single throw of a coin, what is the probability of getting a tail?
3

In a single throw of two coins, find the probability of getting (i) both tails, (ii) at least 1 tail,(iii) at the most 1 tail.
4

A bag contains 4 white and 5 blue balls. They are mixed thoroughly and one ball is drawn at random. What is the probability of getting (i) a white ball? (ii) a blue ball?
5

A bag contains 5 white, 6 red and 4 green balls. One ball is drawn at random. What is the probability that the ball drawn is (i) green?(ii) white? (iii)non-red?
6

In a lottery, there are 10 prizes and 20 blanks. A ticket is chosen at random. What is the probability of getting a prize?
7

It is known that a box of 100 electric bulbs contains 8 defective bulbs. One bulb is taken out at random from the box. What is the probability that the bulb drawn is (i) defective? (ii) non-defective?
8

A die is thrown at random. Find the probability of getting (i) 2 (ii) a number less than 3 (iii) a composite number (iv) a number not less than 4.
9

In a survey of 200 ladies, it was found that 82 like coffee while 118 dislike it. From these ladies, one is chosen at random. What is the probability that the chosen lady dislikes coffee?
10

A box contains 19 balls bearing numbers 1, 2, 3 ..., 19 respectively. A ball is drawn at random from the box. Find the probability that the number on the ball is (i) a prime number (ii) an even number (iii) a number divisible by 3.
11

One card is drawn at random from a well-shuffled deck of 52 cards. Find the probability that the card drawn is (i) a king (ii) a spade (iii) a red queen (iv) a black 8.
12

One card is drawn at random from a well-shuffled deck of 52 cards. Find the probability that the card drawn is (i) a 4 (ii) a queen (iii) a black card.

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