Basic, algebraic percent questions are common on the ACT test. They range in difficulty from simple & straightforward to confusing & challenging. One question might ask you to find out what percent is a number out of another number. Others might include multiple percents in the same problem. Most percent questions on the ACT can be solved using the same, three-part formula. percent = part/whole x 100
Percent means 100th. A percent is 1/100th of something. You can change a percent into a decimal by adding a decimal point two places to the left and drop the percent sign. 15%= .15 You can change it to a fraction by writing it over 100. 15/100
The most common types of percent questions are
- Percent Taken Off
- Percent Change
- Combined Percents
Percent Taken Off- The question will either give you a whole and ask you to find a new value when a percent is taken off. For example, a purse at $80 is discounted 10%. What is the price of the discounted purse? First, subtract the percent from 100 (equals 90). Then, convert 90% into a decimal->( .90) Last, multiply the decimal by the whole amount .90 x 80 =72. Your answer is $72.00.
Percent Change- This question will give you a value and a new value, and ask you to find the percent increase or decrease between those values. Using the same example above, the question might ask if a purse that cost $80.00 was discounted to $72.00, what percent was the discount? The answer is 10%
Combined Percents- This question will give you a whole value, then take a percent off of the whole value twice consecutively. Here’s an example: A purse retailed for $80.00 on Monday. It was discounted 10% one day, and 20% the next day. What is the total percent discount applied to the purse? The answer is a $24.00-discount because the cost of the purse was $56.00 after the combined 30% discount.