Chance and Probability

Q. Fill in the blanks
Question 22
The probability of an event which is certain to happen is ___.

Q. Question 10
In a school, only 2 out of 5 students can participate in a quiz. What is the chance that a student picked at random makes it to the competition?
(a) 20%
(b) 40%
(c) 50%
(d) 30%

Q. Question 4
A box contains two pairs of socks of two colours (black and white). I have picked out a white sock. I pick out one more with my eyes closed. What is the probability that it will make a pair?

Q.

A random variable $X$ has the following probability distribution.

$X$	$1$	$2$	$3$	$4$
$P\left(X\right)$	$k$	$2k$	$2k$	$4k$

Then the mean of $X$ is

1. $3$

2. $1$

3. $4$

4. $2$

Q.

A coin is tossed 400 times and outcomes are
Tail: 220
Head: 180.

(i) What is the probability of getting a tail?
(ii) What is the probability of getting a head? [2MARKS]

Q. Question 12
On tossing a coin, the outcome is
(a) only head
(b) only tail
(c) neither head nor tail
(d) either head nor tail

Q. Question 32
State whether the statements are True or False.
If a die is thrown, the probability of getting a number greater than 6 is 1

Q.

A number is selected from the numbers $2,3,3,5,5,5,7,7,7,7,9,9,9,9,9$ at random. Find the probability that the number selected is their median.

Q. If a card is chosen from a standard deck of cards, what is the probability of getting a five?

1. $\frac{4}{52}$
2. $\frac{1}{52}$
3. $\frac{3}{52}$
4. $\frac{8}{52}$

Q. Question 7
There are 2 aces in each of the given set of cards placed face down. From which set are you certain to pick the two aces on the first go?
(a)

(b)

(c)

(d)

Q.

A survey was conducted to find out the favourite colour among people. 30 people said white, 25 said black, 50 said red and 95 liked other colours. What is the probability of a person selected at random having white as their favourite colour? [1MARK]

Q. Question 63
Classify, the following events as certain to happen, impossible to happen, may or may not happen.
(a) Getting a number less than 1 on throwing a die.
(b) Getting head when a coin is tossed.
(c) A team winning the match.
(d) Christmas will be on 25 December.
(e) Today moon will not revolve around the earth.
(f) A ball thrown up in the air will fall down after some time.

Q. Question 62
The letters were written on paper slips of the word MEDIAN and put in a bag.
If one slip is drawn randomly, what is the probability that it bears the letter D?

Q.

What if the probability is greater than $1$?

Q.

A coin is flipped to decide which team starts the game. What is the probability that your team will start?

Q. Question 33
State whether the statements are True or False.
When a coin is tossed, there are 2 possible outcomes.

Q. Question 56
Following cards are put facing down :
$\begin{array}{ccccc}A& E& I& O& U\end{array}$

What is the chance of drawing out
(a) a vowel
(b) a card marked U?
(c) A or I
(d) a consonant?

Q. Question 2(i)
There are 6 marbles in a box with numbers from 1 to 6 marked on each of them.
What is the probability of drawing a marble with number 2?

Q. Question 16
12 defective pens are accidently 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.

Q.

Which number cannot represent a probability?

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

2. $1.5$

3. $0.7$

4. $15\%$

Q. Fill in the blanks
Question 31
Rohit collected the data regarding weights of students of his class and prepared the following table:
$\begin{array}{ccccc}Weight\left(inkg\right)& 44-47& 48-51& 52-55& 56-59\\ Numberofstudents& 3& 5& 25& 7\end{array}$
A student is to be selected randomly from his class for some competition. The probability of selection of the student is highest whose weight is in the interval ___.

Q.

Which of the following experiments does NOT have equally likely outcomes?

1. Choose a number at random from 1 to 7

2. Choose a letter at random from the word SCHOOL

3. Tossing a coin

4. None

Q. Question 59
What is the probability of the sum setting tomorrow?

Q.

A box contains pairs of socks of two colours (black and white). I have picked out a white sock. I pick out one more with my eyes closed. What is the probability that it will make a pair?

Q. Question 40
State whether the statements are True or False.
The probability of getting an ace out of a deck of cards is greater than 1.

Q.

Tell whether the following is certain to happen, impossible, can happen but not certain.

$\left(i\right)$ You are older today than yesterday.

Q. Question 61
What is the probability that a student chosen at random out of 3 girls and 4 boys is a boy?

Q. Question 60
When a spinner with three colours given in figure is rotated, which colour has more chance to show up with arrow than the others?

Q.

What is the probability of getting an ACE from a deck of well-shuffled cards if the total number of cards are 52 and there are 4 ACEs in it?

1. 2/13

2. 3/13

3. 1/13

4. 4/13

Q.

Seven boys put their names in a basket. If one of these boys draws a name from the basket, what is the chance he draws his own name?