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Tutorial

[MUSIC PLAYING] Let's look at our objectives for today. We'll start by looking at percent as part of a whole. We'll then look at what it means to find the percentage of a number. We'll look at three different methods for finding the percentage of a number. And finally, we'll do some examples finding the percentage of a number.

Let's start by looking out what a percentage is. A percentage is a number that relates a part to the whole. Percentages are viewed as portions of 100. The word percent literally means per 100.

Percentages can be expressed in percent form, decimal form, and fraction form. For example, 45 percent can be written as 45%, 0.45, or 45/100.

Now, let's look at what it means to find the percentage of a number. Suppose in a recent survey 1,200 people were asked if they would vote for a certain candidate. The results showed that 50 percent said, yes, they would vote for the candidate.

We can see from the pie graph that 50% is the same as one half. In fraction form we can see that 50% is one half because 50% equals 50/100 which simplifies to 1/2. This also means that out of all the people surveyed, 1,200 people said, yes, they would vote for the candidate, because half of 1,200 is 600.

Let's look at another example. Suppose in a recent survey 400 people were asked if they owned a car or a truck. The results showed that 25% owned a truck. We can see from the pie graph that 25 percent is the same as one fourth. In fraction form, we can see that 25% is one fourth because 25% can be written as 25/100, which simplifies to 1/4.

So this means that out of all the people surveyed, 400 people, 1/4 or 100 people own a truck, because 1/4 or a quarter of 400 is 100.

Let's look at the methods we can use to find the percentage of a number. There are three ways to find the percentage of a number. I'll start by giving a quick example of each method. And then we'll go more into depth with each method in a minute.

Suppose we want to find 60% of 2,000. The first method is to multiply 60 by 2,000 and then divide by 100. So we have 60 times 2,000, which is 120,000 divided by 100 gives us 1,200.

The second method is to write 60% as a fraction and then multiply it by 2,000. So we have 60/100 times 2,000, or 2,000/1, which equals 120,000/100, which equals 1,200.

The third method is to write 60% as a decimal and then multiply by 2,000. So we have 0.60 times 2,000, which again equals 1,200.

So as you can see, regardless of which method we use, we see that 60% of 2,000 is 1,200.

So now let's look at some real world examples of finding the percentage of a number, using all three methods we just described. In all three methods, you may have noticed that we use multiplication to find the percentage of a number. That's because the word "of" in math often times means multiplication. As in our last example, finding 60% of 2,000, we used multiplication and multiplied 60% by 2,000.

So let's look at a few real world examples using our three methods. Suppose in a 2,000 calorie diet, 55% of your calories should be from carbohydrates. How many of your calories should be from carbohydrates?

To answer this, we need to find 55% of 2,000. Using our first method, we multiply 55 times 2,000, which equals 110,000. We then divide by 100, which gives us 1,100. So 1,100 calories of our diet should have come from carbohydrates.

Here's another example. Suppose a basketball player's free throw percentage is 65%. In a certain game, she attempted to make 6 free throws. So how many successful free throws would you expect her to have made?

Using our second method, we want to find 65% of 6 free throws. We write 65% as a fraction, 65/100. We then multiply by 6, or 6/1. So we have 65/100 times 6/1.

Multiplying across numerators gives us 390. And multiplying denominators gives us 100. Dividing 390 by 100 gives us 3.9. Rounding to the nearest percent gives us 4 free throws made during the game.

For our last example, suppose we have a sale where all jewelry is 30% off. If a necklace costs $50, we want to find how much money we will save. We need to find 30% of $50.

Using our third method, we want to write 30% as a decimal. We know that 30% is the same as 30 over 100. And dividing 30 by 100, we see that it's equal to 0.30.

Now we multiply 0.30 by 50 to see that the answer is 15. So we will save $15 on the necklace.

So let's go over are important points from today. Make sure you get them in your notes so you can refer to them later.

A percentage is a number that relates a part to the whole. Percentages are viewed as portions of 100. The word percent literally means per 100.

Percentages can be expressed in percent form, decimal form, and fraction form. Finding the percentage of a number means finding the portion of the number which is equivalent to the percentage out of 100. And finding the percentage of a number can be done using one of three methods, all which involve multiplying the percentage by the number.

So I hope that these important points and examples helped you understand a little bit more about finding a percentage. Keep using your notes and keep on practicing and soon you'll be a pro. Thanks for watching.

00:00 - 00:39 Introduction

00:40 - 01:11 Percent as Part of a Whole

01:12 - 02:42 Finding Percentage of a Number

02:43 - 04:06 Methods for Finding Percentage of a Number

04:07 - 07:05 Examples Finding the Percentage of a Number

07:06 - 08:07 Important to Points to Remember

Formulas to Know

- Percentage of a Number