NCERT Book Class 7 Maths Chapter 3 Data Handling

44 MATHEMATICS

Chapter 3
Data
Handling

3.1 REPRESENTATIVE VALUES
You might be aware of the term average and would have come across statements involving
the term ‘average’ in your day-to-day life:
l Isha spends on an average of about 5 hours daily for her studies.
l The average temperature at this time of the year is about 40 degree celsius.
l The average age of pupils in my class is 12 years.
l The average attendance of students in a school during its final examination was
98 per cent.
Many more of such statements could be there. Think about the statements given above.
Do you think that the child in the first statement studies exactly for 5 hours daily?
Or, is the temperature of the given place during that particular time always 40 degrees?
Or, is the age of each pupil in that class 12 years? Obviously not.

Then what do these statements tell you?
By average we understand that Isha, usually, studies for 5 hours. On some days, she
may study for less number of hours and on the other days she may study longer.
Similarly, the average temperature of 40 degree celsius, means that, very often, the
temperature at this time of the year is around 40 degree celsius. Sometimes, it may be less
than 40 degree celsius and at other times, it may be more than 40°C.
Thus, we realise that average is a number that represents or shows the central tendency
of a group of observations or data. Since average lies between the highest and the lowest
value of the given data so, we say average is a measure of the central tendency of the
group of data. Different forms of data need different forms of representative or central
value to describe it. One of these representative values is the “Arithmetic mean”. You
will learn about the other representative values in the later part of the chapter.