Compute Percentages

In mathematics, a percentage is a way of expressing a number as a fraction of 100 (per cent meaning "per hundred" in French). It is often denoted using the percent sign, "%", or the abbreviation "pct". For example, 45% (read as "forty-five percent") is equal to 45 / 100, or 0.45. Let us see how to do percentages.                                                                                                                                           - Source from Wikipedia

How to compute percentages:

STEP 1: While begin the percentage` x / 100 ` = `(is) / (of)` . Out of hundred x may be the percentage, "is" denotes as fraction, and "of" denotes as whole.
STEP 2: If we are having the questions 80 : 40 percentage then we will write it as X = 40, is = 40 ("80 is"), and then of = as unknown value. Now the value is possible to write like this `40 / 100 ` = `80 / x` .
STEP 3: Let us do the cross multiplication. Now we can get a Constant value on 1 side and then multiply it with another side. Now we will get a result likes this 40x = 8,000.
STEP 4: Now you have to find out the x value. Where, x = `8000 / 40` = 200, now the x value will be 200.

How do you solve percentages some examples here:

Problem 1:
           In a question paper there is 80 questions. Laura took that test. If she gets 75% correct, how many questions did Laura missed?
Solution:
            Therefore total correct answers are 75% of 80 or else `75 / 100` × 80
            ` 75 / 100` × 80 = 60%
            So the question paper contains 80 questions and Laura got 60 exact answers, the number of questions Laura left is 80 − 60 = 20.
            Therefore Laura missed 20 questions.
Problem 2:
            Compute this, what is 85% of 15?
Solution:
Step 1: Compute the percent.
           The percent value is 85.
            P = 85
Step 2: Find out the base.
           The base is the number next the word OF, 15
            b = 15
Step 3: Identify the quantity.
           The calculation is the unknown.
            a =?
Step 4: Enter the value in the percent proportion formula.
         `a/ 15` = `85 / 100`
Step 5: Exercises the equation for the unknown.
           The Least Common Divisible of 15 and 100 is 100
     `100 / 1` * `a / 15` = `100 / 1` * `85 / 100`
            6.6a = 85
          ` (6.6a) / (6.6)` = `85 / (6.6)`
            a = 12.8
            12.8 is 85% of 15.


Practice problem for compute percentages:
Problem 1:
            What is the percentage of 67%?
Solution:
             = 0. 67.
Problem 2:
            What is percentage of 87% of 18?
Solution:
             = 15.66
            Therefore 15.66 is 87% of 18.