Welcome to this IRSC Adult Education Live Virtual Lesson Diana Lenartiene, Ed. S. moderator/instructor

Elluminate Meeting/Classroom 2 Introducing… your virtual classroom 6/10/2008; updated: 10/3/11

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Percents Percent of a number Percent formula Percent word problems

You can recognize a percent by its symbol: % Examples of percent: 50%, 75%, 23%, 100%, 8% …

Percent means per hundred. The 100 represents one whole thing. For example, if there are 23 students in a class, then 23 is 100% of that class. Most of us are familiar with percent as grades, taxes, or interest rates.

In the following pictures the unit is represented by the entire circle. Notice how the yellow slice can be expressed in three different ways: as a fraction, a percent, or a decimal. We have a recorded lesson on how to convert them if you need practice.

We are fortunate to have a formula we can use which will help us work with percent. The formula is a proportion. We will learn more about proportion in an upcoming lesson. Is = % Of 100 These words may look confusing right now, but as we move into finding the values, it will all make sense.

Let’s try a problem using the percent formula Problem: 25 is what percent of 60? Use the formula to find out! Is = 25 Percent = ? Of = (always the same)

Now we cross-multiply. We will name the unknown number X. 25 = X So 25 x 100 = 60 x X Or 2500 = 60X. Then, we divide to find out what X equals ,

We now have our answer, % The formula will help us find any of the numbers that we need to find. Let’s try another one. Problem: 30 % of 90 is what number? Is = ? 30% Of = Go ahead and cross-multiply then divide to see what you get. The answer is on the following slide.

100X = = 27 So X = is 30% of 90!

18 Percentage Questions Choosing Part and Whole cents

19 Decide what the numbers mean Janet got 34 correct on an exam for a score of 85%. How many were on the exam? Highlight the question. Circle the information. Decide where the numbers belong.

20 Janet got 34 correct on an exam for a score of 85%. Fill in the ratio equation. Solve. 34 is the part X is the whole 85 is the percent

21 Decide what the numbers mean Randall got 28 out of 30 correct. What was his percentage? Highlight the question. Circle the information. Decide where the numbers belong. Is 28 part of the questions or all the questions? Fill in the ratio diagram.

22 Randall got 28 out of 30 correct. What was his percentage? 28 is the part 30 is the whole X is the percent

23 Decide what the numbers mean Walter got a 95% on a quiz with 57 questions. How many did he get correct? Highlight the question. Circle the information. Decide where the numbers belong. Is 57 part of the questions or all the questions? Fill in the ratio diagram.

24 Walter got a 95% on a quiz with 57 questions. How many did he get correct? x is the part 57 is the whole 95 is the percent

25 Randall got 28 out of 30 correct. What was his percentage? 28 is the part 30 is the whole X is the percent

Georgia will receive a 5% commission for selling an $85,000 home. How much did she earn? Hint! Use the proportion formula!

Set up the proportion and solve: X = 5% $85, % Now cross multiply 100X = 425,000 Then Divide by ,000 ÷ 100 = $4,250. Her commission is $4,250.

We have learned:  That we can use the proportion formula to find a part, the percent, or the whole thing  That percent means hundredths.  That we can convert between fractions, decimals and percent (Review from a previous lesson)

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