Find the number A if known number B which greater (less) than A by P percent.
Formula for calculating the number A if known number B which is greater than A by P percent.
If we have the number B, which is greater then A by P percent and need to find A, then
| A = | B · 100% |
| 100% + P |
Formula for calculating the number A if known number B which is less than A by P percent.
If we have the number B, which is less then A by P percent and need to find A, then
| A = | B · 100% |
| 100% - P |
For the derivation of this equation using the method of solving problems with percentage
If "Part" more then "All" by P percent then
have proportion
| "All" | = | 100% | => | "All" = | "Part" · 100% |
| "Part" | 100% + P | 100% + P |
If "Part" less then "All" by P percent then
have proportion
| "All" | = | 100% | => | "All" = | "Part" · 100% |
| "Part" | 100% - P | 100% - P |
Examples of calculating number A if known number B which greater (less) than A by P percent.
Example 1.
Find the number if 66 greater then this number by 10%.
Solution.
| 66 · 100% | = 60 |
| 100% + 10% |
Answer: 60.
Example 2.
Find the number if 63 less then this number by 10%.
Solution.
| 63 · 100% | = 70 |
| 100% - 10% |
Answer: 70.
Example 3.
Client put money on deposit in the bank at 12% per annum, a year later the he have $ 33,600. How much money client put on the deposit?
Solution.
| 33,600 · 100% | = 30,000 |
| 100% + 12% |
Answer: client put on the deposit $ 30,000.
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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