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Math F1 4.3

This document defines proportions as equal ratios or rates, illustrated with examples involving the mass of beans and electricity costs. It explains how to determine unknown values in proportions using the unitary method, proportion method, and cross multiplication method. The final example calculates the cost of electricity for 30 kWh as RM6.54.

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hanisah azhar
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65 views2 pages

Math F1 4.3

This document defines proportions as equal ratios or rates, illustrated with examples involving the mass of beans and electricity costs. It explains how to determine unknown values in proportions using the unitary method, proportion method, and cross multiplication method. The final example calculates the cost of electricity for 30 kWh as RM6.54.

Uploaded by

hanisah azhar
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Proportions

4.3 Proportions

Definition
A relationship that states that two ratios or two rates are equal.

Proportion can be expressed in the form of fraction.

Example
If 10 beans have a mass of 17 g, then 30 beans have a mass of 51 g.

Thus, the proportion is,

17 g 51 g
= .
10 beans 30 beans

Determine an unknown value in a proportion:

Example
The electricity costs 43.6 sen for 2 kilowatt-hour (kWh).

How much does 30 kWh cost?

i) Unitary method

The cost of electricity for 2 kWh is 43.6 sen.

So, the cost of electricity for 1 kWh is


43.6 sen
=
2

= 21.8 sen.

Thus, the cost of electricity for 30 kWh is


= 30 × 21.8

= 654 sen.

ii) Proportion method

Let the cost of electricity for 30 kWh be x sen.


43.6 sen x sen
=
2 kWh 30 kWh

We can see that

2 kWh × 15 = 30 kWh.

Thus,

x = 43.6 × 15

= 654.

iii) Cross multiplication method

Let the cost of electricity for 30 kWh be x sen.

43.6 x
:
43.6 x
=
2 30

2 × x = 43.6 × 30

1 308
x=
2

= 654.
   
Quiz methods,
From these Videos theNotes Account consumption for 30
cost of electricity kWh is RM6.54.
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