The method of solving problems with percentage
All ratios and formulas for solving problems with percent, are derived from the proportion.
Data of the tasks with percents can be written as the following relations:
| All | - | 100% |
| Part | - | Part in % |
which can be written as a proportion
| All | = | 100% |
| Part | Part in % |
Using this proportion, you can get a formulas for the solution of basic types problems with percent.
Examples of task with percent
Example 1.
Find 15% of 30.
Solution.
| 30 | is | 100% |
x | is | 15% |
write proportion
| 30 | = | 100% |
x | 15% |
solve the equation
x = | 30 · 15% | = 4.5 |
| 100% |
Example 2.
35 is what percent of 20?
Solution.
| 20 | is | 100% |
| 35 | is | x |
write proportion
| 20 | = | 100% |
| 35 | x |
solve the equation
x = | 35 · 100% | = 175% |
| 20 |
Example 3.
20 is 5% of what?
Solution.
x | is | 100% |
| 20 | is | 5% |
write proportion
x | = | 100% |
| 20 | 5% |
solve the equation
x = | 20 · 100% | = 400 |
| 5% |
Percent
Percent Definition. Main information
Decimal to Percent. Percent to Decimal
The method of solving problems with percentage
The most common types of problems with percent:
Find P percent of A
B is P percent of what?
B is what percent of A?
Find the number which is greater (less) than a given number by P percent
Find the number A if known number B which greater (less) than A by P percent
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