Question

What percent of 70 is 21?

Answer 1

Hint: We shall use the concept of percent and percentage to solve this question. We are required to find what percent of 70 is 21. This can be done by assuming the percent to be a variable x. This means that $x\%$ of 70 is 21. We represent this in the form of an equation by replacing the percent sign by $\dfrac{1}{100}$ and simplifying for x.

Complete step by step answer:
In order to solve this question, let us assume the percent of 70 which gives 21 be x. This means that $x\%$ of 70 is 21. This is given in word form now. We now represent this in the mathematical form as follows:
$\Rightarrow \dfrac{x}{100}\times 70=21$
Now we simplify this by dividing both sides by 70 first,
$\Rightarrow \dfrac{x}{100}=\dfrac{21}{70}$
The highest common factor for 21 and 70 is 7. We cancel out this common factor and write the equation as,
$\Rightarrow \dfrac{x}{100}=\dfrac{3}{10}$
We now multiply both sides of the equation by 100.
$\Rightarrow \dfrac{x}{100}\times 100=\dfrac{3}{10}\times 100$
The terms in the left-hand side gets completely cancelled and dividing 100 by 10 on the right-hand side gives us 10,
$\Rightarrow x=3\times 10$
Multiplying the two terms on the right-hand side of the equation,
$\Rightarrow x=30$

Hence, $30\%$ of 70 is 21.

Note: It is important to know the basic concepts of percent and percentage. Percent means per hundred. Here, cent stands for one hundred. Another method to solve this question is by dividing the two terms such that 21 lies in the numerator which is the result and 70 lies in the denominator. This gives us a fraction. This fraction multiplied by 100 gives us the percent value.