1. DRAW HISTOGRAMS
2. DRAW FREQUENCY POLYGONS
3. DRAW OGIVES (CUMULATIVE FREQUENCY
CURVES)
4. CALCULATE VARIANCE AND STANDARD
DEVIATION OF UNGROUPED DATA;
5. DETERMINE WHETHER DATA IS SYMMETRIC OR SKEWED
6. IDENTIFY THE VALUES OF THE OUTLIERS.
7. NEW DRAW SCATTER PLOT (analyse trend (linear, quadratic
& exponential , OUTLIER(point) ,correlation coefficient(r) & intreprete r,
Mean point, equation for the least squares regression line (line of best fit)
and draw it, Interpolation and Extrapolation.
BY MR M. SHABALALA @NOMBUSO Page 2
, 1.DRAW HISTOGRAMS
➢ A histogram gives us a visual interpretation of GROUPED DATA. It
looks very similar to a bar graph, but there are NO gabs between the
bars.
➢ In HISTOGRAM INCLUDE THE FOLLOWING
✓ Tittle on top that describe what is contained in
histogram
✓ Group/class intervals in x axis
✓ Frequency in y axis
✓ Bars with no gabs in between
EXAMPLE 1
The frequency table below represents the distribution of the amount of
time (in hours) that 80 high school learners spent in one week watching
their favourite sport.
a) Draw a histogram to represent the data
b) Calculate the modal interval
c) Calculate an estimate of the median.
BY MR M. SHABALALA @NOMBUSO Page 3
, 2.DRAW FREQUENCY POLYGON
➢ Drawn from HISTOGRAM by joining the midpoints of
the top of the columns of the histogram. At the ends, extend
line to the midpoints of class below lower values and the
midpoint of the class above upper value to touch x
axis(grounded)
➢ It can also be drawn by calculating midpoints of interval
and plot coordinate (midpoint, frequency)
EXAMPLE 1
Eighty of the learners at King X High School were surveyed
to find out how many minutes each week they spent collecting
waste material for recycling. The grouped frequency table
shows the results of the survey.
a) Use the frequency table
to draw a histogram
and then draw a
frequency polygon
on the histogram.
b) Find the midpoint of the
Intervals
c) Use the table to draw a
frequency polygon on a
separate set of axes.
BY MR M. SHABALALA @NOMBUSO Page 4
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