Page 184 - Start Up Mathematics_6

Construction of a bar graph
Following are the steps to construct a bar graph.
Step 1: On a graph sheet, draw two mutually perpendicular lines. One line should be horizontal
and the other vertical.

Step 2: Usually we represent the information on horizontal line with uniform gap.
Step 3: Choose a suitable scale. The height of the bars should be proportional to the corresponding
numerical values.

Step 4: Draw bars of equal width and height as explained in the previous step. The centre of
each bar should be on the equidistant points marked on the horizontal axis.

Properties of bar graphs
1. Bars can be either horizontal or vertical.

2. The height or length of a bar represents the numerical value of the data.
3. The width of each bar is kept same, though it is merely for attraction.
4. The distance between any two consecutive bars should be equal.

5. Bars can be shaded, hatched or coloured to make them look attractive.
6. Bar graphs are of one dimension. Only their height is of scale significance.

Example 8: Observe the bar graph depicting the number of students in class VI of a school in
various academic years. 1 unit length = 1 student
Now answer the following questions:

(a) What information is provided by 300
the bar graph? Number of students 250
200
(b) How does the strength of the class 150
100
change over various years? 50
0
(c) In which year were the number of 2005–06 2006–07 2007–08 2008–09 2009–10
Academic years
students maximum?
(d) Correct the following statement:

“The number of students in the academic year 2007–08 is three times the number
of students in the year 2005–06.”

Solution: (a) The bar graph represents the number of students in Class VI of a school during
the academic years 2005–06 to 2009–10.
(b) For 3 consecutive years the strength of the students increased uniformly and
then it decreased in the year 2009–10.
(c) The number of students was maximum in the year 2008–09.

(d) The number of students in the year 2007–08 was 200, twice that of 100 in the
year 2005–06.

Example 9: Observe the given bar graph which shows the marks obtained by Rehman in final
examination in different subjects.

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