Question

$ (7.9\% \,of\,134) - (3.4\% \,of\,79) = x $ . The value of $ x $ is
A.8.1
B.7.8
C.7.9
D.7.3

Answer 1

Hint: In mathematics, a number or ratio expressed as a fraction of 100 is known as a percentage. In everyday life, the percentage is most important in financial aspects. The percentage tells the amount of a substance that is the proportion of a larger sum of substance. In the given question, the numbers 134 and 79 are larger amounts and their proportions that are 7.9% and 3.4% respectively have to be calculated. After calculating them, their difference can be easily found out.

Complete step-by-step answer:
Given,
  $ (7.9\% \,of\,134) - (3.4\% \,of\,79) = x $
now,
7.9% of 134 is $ \dfrac{{7.9}}{{100}} \times 134 = 10.586 $
And
3.4% of 79 is $ \dfrac{{3.4}}{{100}} \times 79 = 2.686 $
Now, the difference of 7.9% of 134 and 3.4% of 79 is –
 $
  (7.9\% \,of\,134) - (3.4\% \,of\,79) \\
   = 10.586 - 2.686\\
   = 7.9 \\
   \Rightarrow x = 7.9 \;
  $
So, the correct answer is “Option C”.

Note: The percentage is written in statement form as – “x percent of some amount”. For example, 40 percent of Rs.1200, here Rs.1200 is the whole amount so it is represented by 100%.
The percentage can be calculated by multiplying the given amount/substance with the "percent" divided by 100. In the given example, 40 percent of Rs.1200 is
 $ \dfrac{{40}}{{100}} \times 1200 = Rs.480 $
The percentage is represented by the symbol "%". On dividing the percentage by 100, the percentage is converted into decimal form like 1% in decimal form is 0.01.
Therefore the above example can be rewritten as - 40 percent of 1200 or 0.4 times of 1200.