**Introduction**

Welcome back to another Secondary Math blog post on the topic of Direct Proportion!

In this blog post, we will be answering a **Direct Proportion** question from the **2018 Zhonghua Secondary School (ZHSS) S2E SA1 Examination Paper**.

Keep on reading to learn how to approach questions about the relationship between two variables.

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

**What I'll Be Sharing In This Article**hide

## Let’s Take A Look At This Direct Proportion Question

*Source: Zhonghua Secondary School — 2018 S2E SA1 Examination Paper [Q11]*

### Read Also:

## Thought Process

🧐 What Is The Formula For A Direct Proportion Question? 🧐The formula is

y=kx, where k is a constant. Remember that for direct proportion questions, the only two variables areyandx.

However, you will notice that in the question, there is no *y* or *x* because they are replaced by *A* and *h*.

How can we form our equation then?

We are going to replace *y* with *A,* and *x* with *h*. Meanwhile, *k* will remain the same.

But the question says that *A* is directly proportional, *not to h.* It is directly proportional to the **square root of h**.

So our equation should be:

💭

Remember This When Writing The Equation💭Write down “where k is a constant.” This is important because k is not a variable, k always has to be a constant.

Next, the question says that given that *A* = 10 and *h* = 225, what is the relationship between *A* and *h*?

Whenever the question asks about the relationship of the two variables, which are *A* and *h* in this question, what it wants you to do is to **write down the equation that involves A and h as the variables**.

So in the final stage, when we come up with our equation, we only want to see *A* and *h* as the variables. Any other coefficients should be in numbers.

Therefore, we do not want *k* in our equation because we only want *A* and *h* to be our variables. This means that we need to look for the value of *k*.

Since the question gave us the values of *A* and *h*, we can substitute these values to form the equation:

Let us now solve the equation!

Because *k* is a constant, it will always be 2/3.

From here, we can now come up with our equation with only *A* and *h* as our variables:

## Suggested Answer

## Conclusion

I hope that after reading this blog post, you learned how to approach Direct Proportion questions better and faster!

To summarise the key learning points:

- When faced with any questions about Direct Proportion, remember that the formula is
. Write this on your question paper first!*y*=*kx,*where*k*is a constant - When you are asked to find the relationship between two variables, which are
*A*and*h*in this question, it wants you to write down the equation with only*A*and*h*as variables. Other coefficients should be in numbers.

Stay tuned for more Secondary Math blog posts!

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