Equally Likely Outcomes

Q.

If three coins are tossed simultaneously, then the probability of getting at least one head and tail is _____.

1. $\frac{1}{4}$
2. $\frac{1}{2}$
3. $\frac{3}{4}$
4. $\frac{2}{3}$

Q.

The probabilities of a student getting I, II, and III division in an examination are $\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$10$}\right.,\raisebox{1ex}{$3$}\!\left/ \!\raisebox{-1ex}{$5$}\right.,$, and $\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$4$}\right.$ respectively.

The probability that the student fails in the examination is

1. $\raisebox{1ex}{$197$}\!\left/ \!\raisebox{-1ex}{$200$}\right.$

2. $\raisebox{1ex}{$27$}\!\left/ \!\raisebox{-1ex}{$100$}\right.$

3. $\raisebox{1ex}{$83$}\!\left/ \!\raisebox{-1ex}{$100$}\right.$

4. None of these

Q. The probability of getting 'atmost two heads' on tossing three coins simultaneously is.

1. $\frac{3}{8}$
2. $\frac{1}{2}$
3. $\frac{7}{8}$
4. $\frac{3}{4}$
5. $\frac{5}{8}$

Q. A box contains some black balls and 30 white balls. If the probability of drawing a black ball is two-fifths of a white ball, find the number of black balls in the box.
[3 MARKS]

Q. A bag contains 15 white and some black balls. If the probability of drawing a black ball from the bag is thrice that of drawing a white ball, find the number of black balls in the bag.

Q.

A card is drawn at random from a pack of 52 cards. Find the probability that the card drawn is black or king.

1. 1/2

2. 7/13

3. 15/26

4. 8/13

Q. The faces of a die bear numbers 0, 1, 2, 3, 4, 5. If the die is rolled twice, then find the probability that the product of digits on the upper face is zero.

Q. Question 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?

Q. Question 25 (ii)
Is the following argument correct? Give reasons for your answer.
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 $\frac{1}{2}$.

Q. Question 2 (iv)
Which of the following experiments have equally likely outcomes? Explain.
A baby is born. It is a boy or a girl.

Q.

Assume that boy and girl babies are equally likely. If a couple have three children, find the probability that at least one is a boy. (Give the answer up to 3 decimal places)

1. 0.875

2. 0.75

3. 0.785

4. 0.578

Q. 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?

Q.

Four friends named Ravi, Suresh, Rani, Geetha put their names in a box. A name is picked at random. What is the probability of getting a boy's name

1. $1$

2. $\frac{3}{4}$

3. $\frac{1}{4}$

4. $\frac{1}{2}$

Q.

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?

Q. Question 41(ii)
A bag contains 24 balls of which x are red, 2x are white and 3x are blue. A ball is selected at random. What is the probability that it is white?

Q. Question 27(iii)
A bag contains 10 red, 5 blue and 7 green balls. A ball is drawn at random. Find the probability of this ball being a not a blue ball.

Q. An experiment produces only equally likely outcomes. P (A) is 0.1, find the value of P (B) where A and B are the two different outcomes.

1. 0.1
2. 0.9
3. 0.4
4. 0.2

Q. A lot of 20 bulbs contains 4 defective ones. One bulb is drawn at random from the lot. What is the probability that this bulb is defective?

Q. Three coins are tossed simultaneously. Arrange the given events in increasing order of their probabilities.

1. 1 head
2. At least 2 heads
3. 3 heads
4. Atmost 2 heads

Q. A box contains 12 balls out of which $x$ are blue. If one ball is drawn at random from the box, what is the probability that it will be a blue ball ? If 6 more blue balls are put in the box , the probability of drawing a black ball is now double of what it was before . Find $x$

Q. The probability of getting at least one tail in 4 throws of a coin is__.

1. $\frac{1}{16}$
2. $\frac{15}{16}$
3. $\frac{1}{8}$
4. $\frac{1}{4}$

Q.

A card is drawn at random from a pack of 52 cards. Find the probability that the card drawn is a red card.

1. $\frac{1}{4}$

2. $\frac{1}{2}$

3. $\frac{1}{13}$

4. $\frac{12}{13}$

Q. A box contains 10 red balls and 15 blue balls. One ball from the box is lost. Two balls are then drawn from the box and are found to be red ones. Find the chance that the missing ball is a blue ball.

1. 0.6
2. None of these
3. 15/23
4. 0.347

Q. Q. If three coins are tossed simultaneously, then find the probability of getting at least two heads.

Q. Why is tossing a coin considered to be a fair way of deciding which team should choose ends in a game of cricket?

Q.

A bag contains 12 balls of which 'x' are white.
(i) If one ball is drawn at random, what is the probability that it will be a white ball?
(ii) If 6 more white balls are put in the bag, the probability of drawing a white ball will be double than that in case (i), Find x. [4 MARKS]

Q. Question 27(ii)
A bag contains 10 red, 5 blue and 7 green balls. A ball is drawn at random. Find the probability of this ball being a green ball?

Q. A box contains 12 balls out of which $x$ are blue. If one ball is drawn at random from the box, what is the probability that it will be a blue ball ? If 6 more blue balls are put in the box , the probability of drawing a black ball is now double of what it was before . Find $x$

Q. 5 different games are to be distributed among 4 children randomly, what is the probability that each child gets atleast one game ?

Q. A box contains 10 red balls and 15 blue balls. One ball from the box is lost. Two balls are then drawn from the box and are found to be red ones. Find the chance that the missing ball is a blue ball.

1. 15/23
2. 0.347
3. 0.6
4. None of these