Essential Education is proud to partner with a variety of instructional designers to bring our students an unmatched educational experience. Check out this recent tip for making sense of percents, from our resident math expert, Harold Lawrance.
What is 40% of 300? If you know percents really well, you can probably tell right away that the answer is 120. But if you’re not sure, there are two ways to solve this problem.
The first method is to write a proportion. That’s when one fraction is equivalent to another. In this case, the fraction 40%/100% is equal to N/300. The number N is what we are trying to find. When you cross multiply, you get 100N = 40300. When you solve for N by divide both sides of the equation by 100, you get 120.
The other method uses algebra. Look closely at the sentence: What is 40% of 300? The word “what” is the number you are trying to find. That’s N. The word “is” means “equals”. The word “of” means times. So, you can write a simple algebraic equation: y = 0.40*300. Notice how I wrote 40% in decimal form. Now you can calculate: 0.40 times 300 is 120.
Both ways give you the same answer, 120.
Which method did you prefer? If you said the first method, you are like most people. However, you shouldn’t completely ignore the second method; it is used later on in algebra.
I hope this clears up and confusion you have about percents!
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