The length of drawing is 4cm and actual length of drawing is 3m. By using formula for calculating representative factor we get value of R.F. as 1:75. R.F. = 4 � 300. The units of both quantities should be same.

Graphical scales are used in survey maps. The graphical scale is drawn on drawing. When drawing ages, engineer?s scale shrinks and may not give accurate results. Hence graphical scale is used as drawing shrinks, scale will also shrink.

A drawing drawn with a scale reading inch units can be read in metric units by means of a metric comparative scale, constructed with a same representative fraction. The comparative scales may be plain scales or diagonal scales and may be constructed separately or one above or.

Origin is at 1st division ending. 1st division is made to sub-divisions. From origin, it is divided into divisions on right side and towards left 1st division is divided into sub-divisions. Here it is asked to measure how many divisions do 2 feet takes. It is 2 from origin to right.

The formula for calculating representative factor is length of drawing divided by actual length of object. Hence for this example, R.F = 20 � 5000 i.e. 1:250. The units of quantities in formula must be same.

Whatever representative factor may given, we just require a number of units to divide line in scale. Representative factor is only needed to find length of scale. Length of scale = Representative fraction x Maximum length.

The smallest value that can be measured is 1 cm or 0.1 dm. The maximum value that can be measured using above scale is 12 dm. 10 cm equals to 1 dm. It is clear that 11 dm can be measured but in addition to it, we can measure 10 cm.

Representative factor is ratio of length represented in drawing to actual length. Here given actual length is 1 m =100cm and length of drawing is 5 cm. R.F. =5 cm/100 cm = 0.05 (or) = 1/20.

Representative factor is ratio of length represented in drawing to actual length. Here given actual length is 1 cm and length of drawing is 30 cm. R.F. = 30 cm/1 cm = 30.

A plain scale is constructed by dividing a line into suitable number of equal parts or units, first of which is sub-divided into smaller parts. Plain scales represent eir two units or a unit and its sub-division.