Question

# If x % of 200 is 10, then what is the value of x.(a). 10(b). 2(c). 5(d). None of these

Hint: Recall the definition of percentage and then find the equation relating x. Solve the equation relating x to find the value of x.

Percentage of a quantity means a fraction of the quantity expressed by taking a hundred as a whole. 100 % means the entire quantity or the whole. The word percent comes from Latin word Per Cent where Centum means hundred.
Percentage is just a convenient way to express a fraction with hundred as a whole.
Percentage is a number expressed as a fraction of 100. It is calculated by multiplying the numeric of the ratio by 100.
To calculate the value of a percentage of some number, we need to multiply that number with the required percentage and divide by 100.
${\text{Percentage = }}\dfrac{{{\text{Required value}}}}{{{\text{Total value}}}} \times 100\%$
Suppose, we have a percentage and want to find the value, we just multiply the percentage with the total quantity and divide by 100.
${\text{Required value = }}\dfrac{{{\text{Total value}} \times {\text{Percentage}}}}{{100}}..........(1)$
Hence, x % of 200 is x multiplied with 200 and divided by 100 and it is given to be 10. Using equation (1), we have as follows:
$\dfrac{{x \times 200}}{{100}} = 10$
Solving for x, we get:
$x \times 2 = 10$
$x = \dfrac{{10}}{2}$
$x = 5$
The value of x is 5.
Hence, the correct answer is option (c).

Note: You might choose option (b) as the correct answer if you attempt to solve without using the percentage formula, which is wrong. Remember that percentage is always out of 100.