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Working out Percentage Problem – what is the easiest approach?

For working out percentage easily, you must be able to translate sentence of percent problem into math language. Remember, each and every word of percent problem has some mathematical meaning. Understanding this mathematical meaning of words is the key to working out percentage easily. We illustrate this in following examples:

Example 1

What percent of 30 is 6?

(A)   10%        (B) 20%                 (C) 30%                 (D) 40%

Solution

We translate the sentence into math language

what means  ”X” (unknown value)
of means  ”x” (multiplication symbol)
is means  ”=” (equal to)
percent means “1/100″

Now working out percentage

The answer is (B)

Example 2

3 is 10% of what number?

(A)   10         (B) 20                 (C) 30                 (D) 40

Solution

We translate the sentence into math language

Now working out percentage equation

The answer is (C)

Example 3

What percent of b is 5b?

(A)   50%        (B) 100%                 (C) 300%                 (D) 500%

Solution

Translate sentence of percent problem into math equation

Now working out percentage for X

The answer is (D)

Example 4

If there are 36 girls and 24 boys in a class, what percent of the class are girls?

(A) 20%
(B) 40%
(C) 60%
(D) 67%
(E) 70%

Solution

Total number of students in the class = 36 + 24 = 60

Now working out percent problem

The answer is (C)

Sometimes you can encounter word problems involving percentages on math section of the SAT test; you need not to worry about the difficulty level of the math percent problem. What you have to do is just to break the SAT Math Percent Word Problem into various parts and identify specific words. Now for working out percent problem, translate those specific words into math equation after you have identified them.

Consider following percent problem calculating percentage  easily.

Example 5

In a Chemistry class, 150 students are male and 80 students are female. 20% of the male students and 25% of the female students are medical students. 20% of the male medical students and 40% of the female medical students passed the final exam. What percentage of medical students passed the exam?

(A) 10%
(B) 20%
(C) 26%
(D) 28%
(E) 30%

Solution

For working out percentage break the statement into various parts by translating the sentences as you read the percent problem.

Male students = 150
Female students = 80
20% of the male students = 20 x 1/100 x 150 = 30 (medical students)
25% of the female students = 25 x 1/100 x 80 = 20 (medical students)
Total medical students = 30 + 20 = 50
20% of the male medical students = 20 x 1/100 x 30 = 6
40% of the female medical students = 40 x 1/100 x 20 = 8
Total number of medical students who passed the final exam = 6 + 8= 14
Now translate last sentence into math equation

Now solving percentage formula

Answer is (D)

Note that “passed the exam” means total students who passed the exam.

 

 

 

 

{ 1 comment… read it below or add one }

Desmond June 18, 2011 at 3:33 pm

This article has given me a clear cut concept of how to work out percentages correctly. Thanks a lot.

Reply

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