Statistical graph: Drawing of bar chart, pie-chart and histogram Cumulative frequency curve Reading and drawing inferences from the graph

Graphical Presentation of data; the diagrammatic representation of collected data is known as the graphical presentation. Statistical data is interpret from graphs, than the use of frequency distribution table, as the graphs give a very clear pictures of data. There are various diagrams or graphs associated with statistics some of these are; BAR CHAT,PIE CHART,HISTOGRAM,CUMMULATVE CURVE(OGIVE),FREQUENCY POLYGON and FREQUENCY CURVE.

THE BAR CHART

This is the using of rectangular bars in representing collected data. Each of the bars in the bar chart are of the same width but different heights, the height of which is proportional to the frequency of the distribution. i.e. the higher the frequency, the taller the bars and the lower the frequency the shorter the bar.In between each of the bars are gaps which are also equal in width. It is not necessary for the spaces and the width of each bars to be the same.Bar chart is used to display qualitative and discrete data.The frequencies are recorded along the vertical axis while the variables are recorded along the horizontal axis.

PIE CHART

This is also known as divided Circles. A pie chart is a circle divided into sectors. Each angles in the sector is proportional to the frequencies. The higher the frequency the higher the Sectoral angles and the larger the sector. To prepare a pie chart,a frequency table is necessary, to display the Variables,Frequecies and the Sectoral angles.

READING ASSIGNMENT:

From your text book,prepare (i) A composite bar chart

                                               (ii) A compound bar chart.Using any suitable question

GENERAL EVALUATION                                                                       

1. The pie chart represents 24hours in the life of a student
2. What fraction of the time is spend sleeping?
3. What percentage of the time is spend studying
4. If 1hr 20 mins is spent travelling, calculate the value of x.

WEEKEND ASSIGNMENT

1. Which of the following is a characteristic of bar chart?(A) The height of each bar is corresponding to the frequency    (B) The Variables are respectively proportional to the width of each bar    (C) The height depends on the frequency    (d) None of the above
2. Calculate the Sectoral angle in a pie chart, with the frequency of 10 and Sum of frequency 36   (A) 100⁰                 (B) 36⁰                 (C) 360⁰                       (D) 72⁰
3. A pie chart is also known as _____________   (A) semi circles             (B) Divided Circles                (C) Circular graph          (D) Angle chart
4. Which of the following is not an example of statistical graph?  (A) Frequency polygon           (B) Frequency curve         (C) Ogive         (D) Quadratic graph
5. A bundle of tally consists ____________ strokes (A) 4     (B) 5     (c) 6      (D) 12

THEORY

1. The number of items produced by a company over a five year period is given below:

YEAR	1978	1979	1980	1981	1982
NUMBER PRODUCED	4100	2500	1500	1800	9200

• Plot a bar chart for this information
• What is the average production for the five year period

2. The table below shows how a company’s sales manager spent his annual salary.

FOOD                                                               30%

RENT                                                                18%

CAR MAINTENANCE                                    25%

SAVINGS                                                         12%

TAXES                                                               5%

OTHERS                                                           10%

• Represent these information on a pie chart
• Find his savings at the end of the year, if his annual salary was N60, 000. 00