Increasing and Decreasing Using Ratios

Ratio Increase Decrease 1
Image Copyright 2012 by Passy’s World

Here at Passy World we have created our own delicious chicken curry which we call “Curry Chicken Tamil Nadu”.

If you would like the recipe for this exquisite dish, then click the following link:

http://passyworldofmathematics.com/pwmPDFs/CurryChickenTamilNaduRecipe.pdf

The Recipe we have made serves four people.

But what if we have 5 people coming over for a curry dinner?

How can we adjust our recipe for 4 people, so that it can feed 5 people ?

We need to use the Mathematics of Ratios !

We need to increase our Recipe in the Ratio of 5 : 4

This makes perfect sense, because Ratios are often used for comparing.

The Ratio of 5 : 4 means we are now feeding 5 people as compared to the recipe’s 4 people.

Remembering that all Ratios can be written as Fractions, we can increase our Recipe by 5 : 4 by simply multiplying all of the Ingredients by 5/4 or one and one quarter.

To Increase a quantity in the Ratio of “b : a”
we multiply the quantity by the fraction “b/a”

Let’s consider the Chicken Curry Spice Mix Quantities.

For Four People we need the following Spice amounts:

1 heaped teaspoon of fennel seeds

2 teaspoons of crushed ground black peppercorns

1 heaped teaspoon of dried red chilli flakes

1/4 heaped teaspoon of ground cardamom seeds

1 flat teaspoon of ground Nutmeg

For Five People we need to multiply all these amounts by 5 / 4

5/4 x 1 = One and one quarter heaped teaspoon of fennel seeds

5/4 x 2 = 10/4 = two and a half teaspoons of black peppercorns

5/4 x 1 = One and one quarter heaped teaspoon of chilli flakes

5/4 x 1/4 = 5/16 heaped teaspoon of ground cardamom seeds **

5/4 x 1 = One and one quarter flat teaspoon of ground Nutmeg

** 5/16 teaspoon of ground cardamom seeds is going to be very hard to measure, and is only 1/16 of a teaspoon extra compared to the original recipe. For this reason we would probably just leave the Cardamom as 1 heaped quarter teapsoon.

As well as the ratio mathematics, we also need to use some common sense when scaling up and down recipes!

So Problem Solved! Five people will be able to come over for dinner and enjoy our delicious chicken curry.

Curry Chicken Tamil Nadu
Image Copyright 2012 by Passy’s World

Note that we can also Decrease Ratios.

For example if only three people were coming to dinner, we could decrease down our recipe in the Ratio 3 : 4 by multiply all our recipe quantities by 3/4.

 
 

Increasing and Decreasing Ratios

To Increase a one teaspoon quantity of Spice in the Ratio of “5 : 4″
we multiplied the quantity by the fraction “5/4″.

The answer came out as “one and one quarter teaspoons”, which was a bigger amount than what we started with.

Ratio Increase One
Image Copyright 2012 by Passy’s World

 

To Decrease an amount in a given Ratio, we need to multiply by a fraction that is less than one.

For example, in scaling down a recipe for four people into a recipe for 3 people, we would use the ratio of 3 : 4 which means we would multiply all our recipe amounts by 3/4.

This will decrease all of the recipe quantities to three quarters of what they were originally.

Ratio Decrease One
Image Copyright 2012 by Passy’s World

 
 

Increasing and Decreasing with Ratios Examples

In the following examples we increase, or decrease, the given amounts by multiplying by the ratio given in the question.

These are fairly easy questions, all we have to do each time is:

Multiply the given numeric Item by the Ratio given in the question

 
 

Ratio Increase Two
Image Copyright 2012 by Passy’s World

 
 

Ratio Decrease Two
Image Copyright 2012 by Passy’s World

 
 

Ratio Increase 3
Image Copyright 2012 by Passy’s World

 
 

Ratio Decrease 4
Image Copyright 2012 by Passy’s World

 
 

Related Items

Introduction to Ratios
Simplifying Ratios
Calculating Ratio Amounts
Fibonacci Sequence in Music

 

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Passy

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