Probability

Q. If a die is thrown, what is the probability of getting a number greater than 5?

1. $\frac{1}{5}$
2. $\frac{1}{6}$
3. 0
4. 1

Q.

$\frac{7}{2}$ is the probability of an event. Explain.

Q.

A die was rolled $100$ times and the number of times, $6$ came up was noted. If the experimental probability calculated from this information is $\frac{2}{5}$, then how many times $6$ came up? Justify your answer.

Q.

A complete cycle of a traffic light takes $60s$. During each cycle the light is green for $25s$, yellow for $5s$ and red for $30s$. At a randomly chosen time, the probability that the light will not be green is

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

2. $\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$4$}\right.$

3. $\raisebox{1ex}{$7$}\!\left/ \!\raisebox{-1ex}{$12$}\right.$

4. $\raisebox{1ex}{$3$}\!\left/ \!\raisebox{-1ex}{$4$}\right.$

Q.

80 bulbs are selected at random from a lot and their life time ( in hours) is recorded in the form of a frequency table given below:

$\begin{array}{cccccc}Lifetime\left(inhours\right)& 300& 500& 700& 900& 1100\\ Frequency& 10& 12& 23& 25& 10\end{array}$

One bulb is selected at random from the lot. The probability that its life is 1150 h, is:

A) $\frac{1}{80}$
B) $\frac{7}{16}$
C) 0
D) ​​​​​​​1​​​​​​​

Q. Consider the following frequency distribution which gives the weight of 38 students of a class:

Weights (in kg)	31-35	36-40	41-45	46-50	51-55	56-60	61-65	66-70	Total
No. students	9	5	14	3	1	2	2	2	38

(i) Find the probability that the weight of a student in the class lies between 36-45 kg.

(ii) Give 2 events in the context, one having probability 0 and the other having probability 1.

Q.

A bag contains $5$ white, $7$ black, and $4$red balls. Three balls are drawn from the bag at random. The probability that the three balls are white, is

1. $3/16$

2. $3/5$

3. $1/60$

4. $1/56$

Q. Give difference and examples of random experiment and deterministic experiment

Q.

The percentages of marks obtained by a student in six unit tests are given below:

If a test is selected at random then, the probability that the student gets more than 60% marks in the test is

1. 

2. 

3. 

4. 

Q.

The probability of getting a multiple of 2 in a throw of an unbiased die is $\frac{1}{2}$.

1. True

2. False

Q.

In a group of students, 50 passed in english, 60 passed in maths and 40 passed in

both.Find the number of students who passed in either English or Maths?

Q. The following table shows the blood groups of 40 students of a class.

Blood group	A	B	O	AB
Number of students	11	9	14	6

One student of the class is chosen at random. What is the probability that the chosen student's blood group is
(i) O?
(ii) AB?

Q.

Fill in the blanks.

(i) Probability of an impossible event = ___

(ii) Probability of a sure event = ___

(iii) Let E be an event. Then, P(not E)= ___

(iv) P(E) + P(not E)= ___

(v) ___$\le$ (P) $\ge$___

Q.

Blood group	Number of students
A	9
B	6
AB	3
O	12
Total	30

The above frequency distribution table represents the blood groups of 30 students of a class. Use this table to determine the probability that a student of this class, selected at random, has blood group AB.

Q.

A teacher wanted to analyse the performance of two sections of students in a mathematics test of 100 marks. Looking at their performances, she found that a few students got under 20 marks and a few got 70 marks or above. So she decided to group them into intervals of varying sizes as follows: 0 − 20, 20 − 30… 60 − 70, 70 − 100. Then she formed the following table:

Marks	Number of student
0 − 20 20 − 30 30 − 40 40 − 50 50 − 60 60 − 70 70 − above	7 10 10 20 20 15 8
Total	90

(i) Find the probability that a student obtained less than 20 % in the mathematics test.

(ii) Find the probability that a student obtained marks 60 or above.

Q. The probability of an event lies between ___________________

Q.

Describe discrete random variable

Q.

A bag contains $6$ red balls and $4$ green balls. Find the probability of selecting at random a green ball?

Q.

In a box, there are $20$ cards out of which $10$ are labelled as $\mathrm{A}$and remaining $10$ are labelled as $\mathrm{B}$. Cards are drawn at random, one after the other and with replacement, till a second $\mathrm{A}$-card is obtained. The probability that the second $\mathrm{A}$-card appears before the third $\mathrm{B}$-card is:

1. $\frac{15}{6}$

2. $\frac{9}{16}$

3. $\frac{13}{16}$

4. $\frac{11}{16}$

Q.

What is $P\left(E\right)$ in probability?

Q.

The probability of an event of a trial is:

1. lies between 0 and 1 (both inclusive)

2. is greater than 1

3. 1

4. 0

Q. Define probability of an event.

Q.

Empirical probability P (E) of an event happening is defined as

1. Number of trials in which the event happened/The total number of trials

2. Number of trials made / Number of trials not mad

3. Number of events / Number of probabilities

4. Number of events happened /Number of events not happened

Q. A coin is tossed 40 times and the head appear 15 times . what is the probability of getting a tail ?

Q.

Which user action will not generate a server-side event?

Q.

If the probability of an event happening is 0.6, what is the probability of the event not happening?

__

Q. Experiments that produce the same results or outcomes when repeated under identical conditions are known as:

1. Deterministic experiments
2. Random experiments
3. Probabilistic experiments
4. Elementary experiments

Q.

An action which results in one or several outcomes is called as a _______.

1. outcome
2. trial
3. sample space
4. none of the above

Q.

A bag contains $3$ red balls and some blue balls. If the probability of drawing a blue ball is thrice that of the red ball, find the number of blue balls in the bag.

Q. We have cards numbered 1 to 52. What is the probability that a card drawn at random has a perfect square?

1. 7/52
2. 1/13
3. 5/13
4. 3/13