P5 Fractions Word Problems: How To Solve With Change Strategies

Introduction

Welcome back to another P5 Fractions blog post!

In this blog post, I will be teaching you one of the Change Strategies, which is another technique you can use to solve P5 Math word problems.

What Are The 4 Change Strategies?

1️⃣ One Item Unchanged

2️⃣ Difference Kept The Same (or Common Difference)

3️⃣ Total Unchanged

4️⃣ All Items Changed

We’ve learned when and how to use the Common Difference Method to solve P5 Math Word Problems in a previous blog post. So I will be discussing when and how to use the Change Strategy One Item Unchanged.

Alternatively, you can watch my explainer video on this question here.

Let’s Take A Look At This Fractions Question

Source: Raffles Girls’ Primary School — 2018 P5 Math SA1 Examination Paper [Q9]

Thought Process

Let us first analyse the question.

Shirley picked some strawberries and raspberries.

But what else do we need to know about them? Let’s read on.

5/7 of the fruits were strawberries and the rest were raspberries.

We can assign these two numbers in the fraction to the two items in the question.

The numerator 5 will go to the first item in the sentence, which is the initial quantity of strawberries.

Meanwhile, the denominator 7 represents the initial total number of fruits.

How do we know this? Because 5 units have been assigned to the strawberries, the remainder of this fraction refers to the rest of the fruits, which are raspberries.

Thus, making the total number of fruits 7 units.

Let us record this information with the label “At First.”

For the strawberries, we have 5 units. How about the raspberries?

Remember that we have 7 units of fruits in total. To get the number of raspberries, we will subtract 5, which is the number of strawberries.

We are going to represent strawberries with S and raspberries with R.

💡 Why Is It Important To Use Letters To Represent Variables? 💡

Using the first letter of the variables for representation helps us save time during examinations.

Now, let us take a look at the third sentence.

Her family ate 30 raspberries.

Therefore, the number of raspberries decreased by 30.

Meanwhile, was there any change in S? Did the question mention anything about the strawberries being eaten or thrown away?

The question did not mention anything. So based on the information that we have, we know that S remains the same.

Let us continue reading the question.

As a result, 10/11 of the remaining fruits were strawberries.

Can you spot the fraction in this sentence?

It’s 10/11!

What does this fraction tell us?

The numerator 10 represents the number of strawberries in the end, while the denominator 11 tells us the total number of fruits in the end.

Let us record this information with the label “End.”

As we did in our first fraction, let us subtract the number of strawberries from the total number of fruits to get the number of raspberries.

With all the information in place, let us ask ourselves — What changed? What did not change?

As indicated in the Change Table, S did not change.

But in the end, S has 10 units.

If there was no change, the 5 units at the start should equate to the 10 units at the end.

How can we make them the same?

To get from 5 units to 10 units, we will multiply 5 by 2.

This means that every unit must first be multiplied by 2 so that S will remain consistent from the start to the end.

With the new units in place, let’s examine R.

At first, R only had 4 units but it ended with 1 unit.

Why is this so?

Let us look at our Change Column.

R decreased because her family ate 30 raspberries.

Let’s find the difference between 4 units and 1 unit.

3u equates to the 30 Rs eaten. So let us write that down and proceed to computing the value of 1 unit.

Therefore the value of 1 unit is 10.

Let us go back to the question. How many strawberries did she pick?

Do we find the S at first or the S at the end?

Let us review. We have 10 units both at first and at the end. Therefore, we can confidently determine that there are 10 units of S.

Answer For Q9

100 strawberries

Conclusion

I hope that after reading this blog post, you’ve learned how to use the One Item Unchanged Method, which is one of the four Change Strategies.

🧐 Did you know that you can use the Change Strategies for these P5 Math topics? 🧐

💯 Whole Numbers

🍰 Fractions

🍕 Ratio

📊 Percentage

🔢 Decimals

Remember also to use the first letter of the variables to represent them in your workings to help you save time when solving P5 Fractions Word Problems.

Stay tuned for more tips on solving P5 Math word problems!