Estimating a Percent of Quantity
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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.


Find 10% of $50


 10% of $50 = n
  Write 10% as a decimal
  Remember "of" means multiply
  0.1 x 50 = n
  n = 5


10% of $50 = $5.00


Another way to find the percent of a number is by writing a proportion.


Find 20% of $60


First, write the percent as a fraction.


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.


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?

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.

Let's Practice!

Topic Index | Grade 6 Math | Intermediate Test Prep | StudyZone

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