Page 28 - WCS - Electrical

WORKSHOP CALCULATION & SCIENCE - CITS

EXERCISE 3 : Percentage

Square root, Ratio and Proportions, Percentage

Percentage

Percentage is a kind of fraction whose denominator is always 100. The symbol for percent is %, written after the
number. e.g. 16%.
16
Ex. = 0.16
100
In decimal form, it is 0.16. Percentage calculation also involves rule of three. The statement (the given data), for
100
unit, and then to multiple which is for calculating the answer. (Fig 1)
3.6
100
3.6

1
76

1
Example 76
The amount of total raw sheet metal to make a door was 3.6 metre and wastage was 0.18 metre . Calculate the
2
984.50
2
X100 =
% of wastage. (Fig 2) 1295.39
76
75
= x 100 = 37 1 %
200 2
15x 100x + 15x
15000 = x + =
100 100

1500000
x = = 13043.47
115
Solution procedure in three steps.
Statement:
16
Area of door (A) = 3.6 m = 100 %.
2
=
0.16
100
Wastage = 0.18 m 2
16
100
Single: x 1 m 100 = 0.16
2
3.6
100
100
Multiple : for 0.18 m = x 0.18

2
3.6
Wastage 3.6 = 5%
100
1
Analyse the given data and proceed to arrive at the answer through the unit.
3.6
76
1
1
76
76
1
984.50
76
X100 = 1295.39
76
984.50
75 X100 = 1295.39
= x 100 = 37 76 1 %
200 2 15
75
100
x
15x = 100x + 15x = 37 1 2 %
15000 = x + = 200
100 100
15x 100x + 15x
1500000 15000 = x + =
x = = 13043.47 100 100
115
1500000
x = = 13043.47
115