Page 202 - Maths Skills - 7

200 Maths

In a bar graph, each rectangle or bar represents
only one value of the numerical data. There are as
many bars as the number of values in the numerical
data. The height or length of each bar indicates,
on a suitable scale, the corresponding value of the
numerical data.

Reading and Interpretation of Bar Graphs
From a bar graph we can compare a given data
visually and can draw certain conclusions. This is
known as reading and interpretation of the bar graphs.

Drawing of Bar Graphs Fig. (b)
In this section, we shall learn how to draw bar graphs on a graph paper when some numerical data are given.
We can draw the graph by following the steps given below:
Step 1. On the graph paper, draw a horizontal and a vertical line such that they are mutually perpendicular. The
former is called the X-axis and the latter is called the Y-axis.
Step 2. Along the X-axis mark points at equal intervals. The names of data items whose values are to be plotted
are written below these points.
Step 3. Choose a suitable scale to determine the heights of the rectangles or bars and then mark the heights on
the vertical Y-axis.
Step 4. Draw bars or rectangles of equal widths and of heights marked in Step 3 on the horizontal X-axis with
equal spacing between them.
The figure so obtained will be the bar graph representing the given numerical data.

Let’s Attempt

Example 1: Read the bar graph given in the Fig. and answer the questions given below.

(i) What information is given by the bar Scale
graph? Y-axis: 10 small divisions = 20 cars
(ii) Give the number of months under
survey.
(iii) In which month was the production at
the minimum level?
(iv) In which month was the production of
cars maximum?
(v) How many cars were produced during
the months under survey?

(vi) Calculate the average number of cars
produced during the months under
survey.

Number of cars produced by an automobile company in a year