GMAT Resources

Percentage Problems

Percentage Problems

Percentages are a great way to express a number as a fraction of 100. It is denoted by the % sign. So, if 50% of the students in a class are absent, it means that half of the class (50\100) is absent. Percentages are very often used to represent increase or decrease in certain values. For eg, the increase in population, the increase/decrease in crude oil prices and other such representations.

Percentage problems on an exam can range from simple ones such as calculating percentages and moderately difficult ones such as increase or decrease in percentages. More advanced questions test combined percent change or finding a number before a percent change.

If you have to measure percentage change, then first identify the original and final values. After identifying these values, calculate the difference between them. The percentage can be easily calculated by dividing the difference between the values by the original value and multiplying by 100.

Let’s take an example question on percentages:

10 is what percent of 25?

For such questions, it always helps if you translate the question into a word problem. Let us keep the unknown answer as x. So, this problem can be easily represented by the equation:

10 = x% (25)

Or 10 = (x/100) (25)

Now you can easily calculate x. In this case, the answer is 40. Therefore, 10 is 40% of 25.

One of the important tricks for percentage questions is representing percentages as fractions or decimals. If x is the percentage, then x\100 is the fraction. Dividing x by 100 gives you the decimal number. Also, make sure you read the question well before attempting percentage problems. The questions are deliberately phrased in a tricky manner to stump students.

Some advanced questions also ask you to determine percent of a percent. A step-by-step approach works well for such questions. You should first calculate the effect of the first percentage change. Once you come up with an answer, use that number to calculate the effect of the second percentage change.

Remember, a little logic is all it takes to solve percentage problems successfully.

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