Estimating a Percent of Quantity Lesson Topic Index | Grade 6 Math | Intermediate Test Prep | StudyZone

Percent means part of a hundred. So, let's look at what 25/100 means. It means the same as 25 out of every 100 and can be written as 25%.

In this lesson we will learn how to estimate percents. But first we will take a look at how to find the percent of a number.

 One way to solve problems using percents is by writing an equation. Problem Find 10% of \$50 Equation 10% of \$50 = n Write 10% as a decimal Remember "of" means multiply 0.1 x 50 = n n = 5 Solution 10% of \$50 = \$5.00

 Another way to find the percent of a number is by writing a proportion. Problem Find 20% of \$60 Proportion First, write the percent as a fraction. 20/100 Next, write as a proportion and solve. 20/100 = n/\$60 \$60 x 20 = 100n Solution n = \$60 x 20/100 or \$12

 Let's take a look at another example. Find 5% of 200. (Remember 5%=0.05) Let n = the answer 0.05 (200) = n 10 = n

Now you're ready to move into estimating percent of a number.

EXAMPLE :
 Estimate Percent of a Number

There are 21 students in Mrs. Carroll's class, and
12 of them are girls.
About what percent of the class is girls?

Solution:
First, round off the numbers to numbers
that are easier to work with.
21 students ≈ 20 students
12 girls ≈ 10 girls
The "rounded" problem becomes 10 out of 20 students are girls.
As a fraction that is 10/20
Reduce the fraction...1/2
1/2 = 50%
A good estimate of the percentage of students in the
class who are girls is 50%.

 Remember: round off to numbers that are easy to work with.

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