1. Estimating with Percents
Estimating is one of those skills that everyone does their own way…if fact there are many ways to estimate and you are essentially all doing the same thing, just the steps are in a different order. This lesson only shows you one way. If you know a different way, that’s great. Our goal today if for everyone to understand how to estimate percents in one way or another. To minimize confusion, please do not shout out your way in the middle of explaining another way.
Lesson 2-6

2. Objectives I can follow 2 steps to find a fraction of a number.
I can use fractions and rates per 100 to estimate a percent of a number.

3. Finding a Fraction of a Number
Step 1: Divide by the denominator
Step 2: Multiply by the numerator.
Example : Find of 60
Step 1: Divide 60 ÷ 3 = 20
Step 2: Multiply 20 x 2 = 40
So, of 60 is 40.

4. Example 1 Estimate 47% of 692. Step 1: Round 47% up to 50 %
Step 3: Solve.
50% of 700 = ?
1 2 of 700 = 350.
So, 47% of 700 is about 350.

5. Example 2 Estimate 60% of 27. Step 1: Convert 60% to a fraction.
= 3 5
Step 2: Round 27 to 25.
Step 3: Solve of 25.
25 ÷5 = 5
5 x 3 = 15
So, 60% of 27 is about 15.
This is just one way…

6. Got It?
Estimate 48% of 76.
Estimate 18% of 42.
Estimate 73% of 41

7. So, a polar bear can eat about 70 lbs of food in 1 hour.
Example 3
Polar bears can eat as much as 10% of their body weight in less than one hour. If an adult male polar bear weighs 715 pounds, about how much food can he eat in one hour?
Step 1: Convert 10% to a fraction
10% = 1 10
Step 2: Round 715 down to 700.
Step 3: Solve
1 10 of 700 =
700 ÷10=70
So, a polar bear can eat about 70 lbs of food in 1 hour.

8. Got It?
c. Kayleigh decided to donate 30% of her savings. If she has $238 in her savings account, about how much will she donate?

9. Example 4
Estimate 17% of 198 using a rate per ≈ % is 17 out of 100. Since 200 = , add to estimate. ≈34

10. Example 5
An airline records the snack orders of passengers. Last year 9 % of all passengers ordered ginger ale to drink. There are 408 passengers on the flight to Houston. About how many passengers does the airline expect to order ginger ale on this flight? Estimate 9% of ≈ x 4 = 36 About 36 people will order ginger ale.

11. Got It?
Estimate using a rate per 100.
d. 27% of 307
e. 76% of 192