NCERT Solutions For Class 12 Geography Chapter 4 Data Processing

(i) A computer is a fast and versatile machine that can perform simple arithmetic operations, such as, addition, subtraction, multiplication, and division and can solve mathematical formulae. It can be used for data processing, preparation of diagrams/graphs and the drawing of maps, etc.

(ii) The following advantages of a computer make it distinct from the manual methods:

• Computer increases the speed of the computation and can handle huge volume of the data.
• It facilitates copy, edit, save, validation, check and retrieves the data.
• It is very easy to perform comparative analysis of data by drawing maps or graphs.
• The type of graph or map, heading, indexing, etc., can be changed very easily.

(iii) MS Excel is also called Spread-sheet or work sheet. A worksheet is made up of cells. A cell can contain a numerical value, a formula or text. An Excel worksheet contains 16,384 rows, numbered 1 through 1,6384 and 256 columns.

(i) (c) Pie-diagram

(ii) (a) Points

(iii) (d) ×

(iv) (a) Construct graphs

(i) Spatial Data: Data, which directly or indirectly referenced to a location on the surface of the earth, and are characterised by the points, lines and the polygons, is called spatial data. The point data represent positional characteristics of the some of the geographical features such as schools, hospitals, wells, villages, etc., on the map. A point shows location of a place. Lines are used to depict linear features like roads, railway lines, rivers, canals, etc. Polygons are used to show area features such as countries, districts, states, blocks; land use types and features like ponds, lakes, etc.

Non–Spatial Data: The data describing the information about spatial data are called as non-spatial data. For example, a map showing positional location of a school with the information like the name of the school, available subject stream, number of students, classes, sections, date of admissions and examination, date of result, etc.

(ii)  The geographical data are available in analogue (map and aerial photographs) or digital form (scanned images).

Analogue data are a physical product displaying information visually on paper, e.g., maps. A mapping software provides functions for spatial and attribute data input through onscreen digitisation of scanned maps, transformation of scale, map design, etc.

Digital data are information in a computer readable form, e.g., satellite data. A digitised map consists of three files, e.g., shp, shx and dbf. The dbf file is dbase file that contains attribute data and is linked to shx and shp files. The shx and shp files contain spatial (map) information. The dbf file can be edited in MS Excel.