The Table X above shows the number of farm units in three villages of Oju District in the year 2010. Use the data in Table X to answer the questions that follow. (a) Using the map of Oju District provided on page 3 and radius of 1 cm to represent 3 farm units, Construct proportional circles to represent the data. (b) State two disadvantages of proportional circles.
Explanation
(a) Construction of proportional circles Calculation of radii of circles using square root method Village (A): √81= 9 using the scale of 1cm to represent 3 farm units =9/3 = 3cm . Village (B): √100 = 10 using the scale of 1cm to represent 3 farm units= 10/3 = 3.3cm Village (C): √64 = 8 using the scale of 1cm to represent 3 farm units = 8/3 = 2.7cm
(b) Disadvantages of proportional circles: - it is time consuming difficult to differentiate among sizes when radii are almost equal - it is difficult to use when groups are many - it is difficult to choose a suitable Scale-it is difficult to work out the mathematical calculations involved - difficult to show large range or data (i.e. data in extreme values) - it is difficult to convert data back into absolute figures once the circles a are Constructed - shape and size of an area on a map may force overlap of circles - the circles do not Snow Spread of items within specific regions - decimal figures in the data are difficult to work with.
