Question

How do you solve the proportion \[\dfrac{5}{{12}} = \dfrac{x}{{36}}\] ?

Answer 1

Hint: Here two ratios are given such that they are in proportion. Now they are in proportion means their simplified forms are the same. But here they are not the same. So we will make them the same by finding the value of x that satisfies the simplified ratio. This is one approach. And we have a second approach that we will cross multiply the numbers to obtain the value of x.

Complete step-by-step answer:
Method 1:
Given that \[\dfrac{5}{{12}} = \dfrac{x}{{36}}\] are in proportion.
So the second ratio should be also in the form such that after simplification it should be the same as the first ratio.
So when 12 is multiplied by 3 we get 36 as the answer.
So we will multiply 5 with 3 to get the answer of x.
\[5 \times 3 = 15\]. This is the value of x.

Method 2:
Here in this method we will cross multiply the numbers such that
\[x = \dfrac{{5 \times 36}}{{12}}\]
On dividing 36 by 12 we get,
\[x = 5 \times 3 = 15\]
This is also correct.
So, the correct answer is “15”.

Note: Proportion means there are two quantities depending on each other are written in ratio form.
Direct and indirect proportion are the two basic types of proportion.
X and Y are said to be in direct proportion if they increase or decrease together, such that the ratio remains constant.
X and Y are said to be in indirect proportion if an increase in X causes proportional decrease in Y, such that their product remains the same.