Data mostly available to us in an unorganized form is called

Arranging data in an order to study their salient features is called presentation of data.

Let’s understand it with an example 20 people were asked for their Favorite IPL team, the answer is

Pune, Mumbai, Mumbai, Kolkata, Delhi, Kolkata, pune, Mumbai, Hyderabad, Bangalore, Mumbai, Pune, Delhi, Mumbai, Pune, Kolkata, Pune, Pune, Hyderabad, pune

It will be difficult to read this data, so we can organize this data into table format
Team |
Number of People |

Pune |
7 |

Mumbai |
5 |

Kolkata |
3 |

Delhi |
2 |

Hyderabad |
2 |

Bangalore |
1 |

Table that shows the frequency of different values in the given data is called a

We can represent Frequency distribution table on Bar graph also

Let’s Understand this with an example

A class of 50 students was given Physics test of Maximum Mark 60. Here is the test score of the students

20,21,22,22,23,25,26,27,27,26,27,26,29,26,27,25,25,30,51,55,46,47,48,41,42,31,34,35,35,36,36,37,37,35,37,39,39,37,36,35,36,36,37,38,38,39,39,43,44,44

If we draw the frequency distribution based on individual marks, it will difficult to understand the data, So for convenience we can group the Marks in equal interval and draw the frequency distribution like below
Class Marks |
Frequency |

20-25 |
5 |

25-30 |
12 |

30-35 |
3 |

35-40 |
20 |

40-45 |
5 |

45-50 |
3 |

50-55 |
2 |

- The above table is called grouped frequency distribution
- 20-25,25-30 are called the class interval
- In 20-25 class interval,20 is called lower class limit and 25 is called the upper class limit
- The common observation like 20,30, etc. belongs to the higher class interval. So25 will belong to 25-30

- A table that shows the frequency of groups of values in the given data is called a
**grouped frequency distribution table** - The groupings used to group the values in given data are called classes or class-intervals. The number of values that each class contains is called the class size or class width. The lower value in a class is called the
**lower class limit**. The higher value in a class is called the**upper class limit.** - The common observation will belong to the higher class.

The time spent by a student during a day.

Sleep — 8 hours

School — 6 hours

Homework — 4 hours

Play — 4 hours

Others — 2 hours

Draw the pie chart

Total hours are 24 hours. Now we need to find fraction of each of the activity with respect to whole day and also the angle subtended by that activity to draw the pie chart

Activity |
Hours |
Fraction |
Central Angle |

Sleep |
8 |
8/24=1/3 |
(1/3) ×360=120 |

School |
6 |
6/24=1/4 |
(1/4) ×360=90 |

Homework |
4 |
4/24=1/6 |
(1/6) ×360=60 |

Play |
4 |
4/24=1/6 |
(1/6) ×360=60 |

Others |
2 |
2/24=1/12 |
(1/12) ×360=30 |

Now to draw the Pie chart, follow the below instructions

1) Draw a circle with any convenient radius. Mark its centre (O) and a radius (OA).

2. Start with one activity, the angle of the sector for sleep is 120°.

Use the protractor to draw ∠ 120°.

3. Continue marking the remaining sectors.

A

Example

Throwing a dice

Tossing the coin

Outcomes of an experiment are

Example

In tossing the coin, both head and tail can come equally likely

In throwing the dice, all the number 1, 2,3,4,5,6 can come equally likely

One or more outcomes of an experiment make an

Example

Getting a tail in tossing a coin is an event

Getting a number 1 or getting number 2 .. in a throw of dice are also event

Getting an odd number in a throw of dice is also an event. The event will contain 1,3,5 as outcome

Probability is calculated as

This is applicable when the all outcomes are equally likely

When a die is thrown, Find the probability of the following

(a) getting prime number

(b) getting not a prime number.

(c) getting a number greater than 4

(d) getting a number not greater than 4.

Total outcome from the dice are 1,2,3,4,5, 6. So 6

a) getting prime number

1,2,3,5 are the prime number

So probability = 4/6= 2/3

b) getting not a prime number

4,6 are not prime number

So Probability = 2/6= 1/3

c) getting a number greater than 4

5,6 satisfies the requirement

So probability = 2/6= 1/3

d) getting a number less than 4

1,2 ,3 satisfies the requirement

So probability = 3/6= 1/2

Go Back to Class 8 Maths Home page Go Back to Class 8 Science Home page

- Biology Foundation Course for AIPMT/Olympiad : Class 9
- Science FR Ninth Class Part-3 (Biology) (PB)
- Physics Part 1 Class - 9
- Chemistry Part 2 Class - 9
- The IIT Foundation Series Physics Class 9
- The IIT Foundation Series Chemistry Class 9
- Oswaal CBSE CCE Question Banks With Complete Solution For Class 9 Term-II (October To March 2016) Science
- x am idea science class 9 term -2
- NCERT Exemplar Problems: Solutions Science Class 9
- NCERT Solutions - Science for Class IX