Tag Archive: inverse proportion

E-Math: How to Translate a "Proportion Statement" Into an Equation

(Photo Credit:Jeff Keen)

I love to use everyday life examples to teach Math Concepts, it's more interesting to me and my students.

Today, I'm going to use the concept of 'See-Saw' to share with you on 'How to Translate a "Proportion Statement" Into an Equation'

At the end of this post, you will be able to translate all types of statement (be it inversely proportion or direct proportion) into an equation (some called it a formula)

Direct Proportion statement:

You need to first understand what's Direct Proportion (Read all about it here)

Let's look at an example: Given y is directly proportional to [pmath]{x^2}[/pmath], write an equation connecting x, y and a constant k.

So, in simple terms, when y increases, x increases too.

Inverse (Indirect) Proportion statement:

Given y is inversely proportional to [pmath]{x+2}[/pmath], write an equation connecting x, y and a constant k.

This is similar to the situation when a See-Saw is in Up-Down position. y is up while (x+2) is down. You can also see it from another point: y is in the numerator while (x+2) is in the denominator or when y increases, x decreases.

I hope you have understand the easier way to translate statements into equations for proportionality question.

In my next post, I will be sharing the various approaches in solving a proportionality question and the hint to look out for in order to use the correct approach.

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E-Math: What is Direct Proportion and Inverse Proportion?

Proportion is a topic taught in Secondary 1 and 2. In fact, we have learnt about direct proportion much younger.

DIRECT PROPORTION

A real simple example of Direct Proportion would be the more money I have, the more things I can buy. When amount of money increases, the number things I can buy increase too. (Notice the increase in both things)

Another example, the less I eat, the thinner I become, so as the amount of food eaten decreases, my weight decreases too.

INVERSE PROPORTION

An example of inverse proportion most of you can relate to would be: the more time I spent on Facebook (PSP, WII, Internet), the less time I have on my books!

Allow me to add in another example of Inverse Proportion, the more I spent, the less I have in my bank.

These are some examples (simple) to understand the true meaning of Direct or Inverse proportion.

In the next post, I will be sharing with you how we can translate a statement into an equation involving proportion. I'm also going to highlight the 'tricky' proportion question in 2008 GCE O Level Elementary Mathematics Paper 1.

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