# Probability

## Trending Questions

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

- 15
- 16
- 0
- 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 25, 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

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

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

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

$\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:

Lifetime (in hours)3005007009001100Frequency1012232510

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

A) 180

B) 716

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

$3/16$

$3/5$

$1/60$

$1/56$

**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

**Q.**

The probability of getting a multiple of 2 in a throw of an unbiased die is 12.

True

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 |

(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)

**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:

$\frac{15}{6}$

$\frac{9}{16}$

$\frac{13}{16}$

$\frac{11}{16}$

**Q.**

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

**Q.**

The probability of an event of a trial is:

lies between 0 and 1 (both inclusive)

is greater than 1

1

0

**Q.**Define probability of an event.

**Q.**

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

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

Number of trials made / Number of trials not mad

Number of events / Number of probabilities

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:

- Deterministic experiments
- Random experiments
- Probabilistic experiments
- Elementary experiments

**Q.**

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

- outcome
- trial
- sample space
- 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?

- 7/52
- 1/13
- 5/13
- 3/13