6th Grade Math Textbook, Fundamentals

0% 26.4%

0 p 244

100%

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7-7

About what percent of 237 is 177?



 Simplify.

75%

So 177 is about 75% of 237.

Choose compatible

numbers.

Write the numbers in

ratio form.

3

4

3

4

180

240

180

240

177

237

177

237

1 Estimate the base if 38.6 is 18.8% of it.
Use the percent formula, and solve for b.
r• bp
18.8% • b38.6 Substitute known values for rand p.
18.8% 20% Change 18.8% to a common percent.
38.6  40

20% • b 40 Substitute 20% for rand 40 for p.

b 40 Use 20% .

b  40  Divide both sides by.

b 200

So the base is about 200.

1

5

1

5

1

5

1

5

1

5

Change the percentage to

a compatible number.

1

5

2

Remember:

Compatible numbersare

numbers that are easy to

compute mentally.

Benchmark Percents

Percent 1% 10% 12 %^12 20% 25% 33 %^13 50% 66 %^23 75%

Fraction 1001 101 18 15 14 13 12 23 34

Decimal 0.01 0.1 0.125 0.2 0.25 0.3 0.5 0.6 0.75

Update your skills. See page 411 X.

Estimate with Percents

Objective To estimate to find percent• To estimate a percent from a model that is not

100 units• To estimate a percent from a three-dimensional model

If a snack pack has a mass of 244 grams and the

percent of carbohydrates is 26.4%, about how many

grams of carbohydrates are in the snack pack?

To find about how many grams, estimate.

r• bp Use the percent formula.

26.4% • 244 p Substitute known values into the formula.

26.4% 25%  Change the percent, r, to a common percent.

244  240 Change the base, b, to a compatible number.

• 240  60 Compute mentally.

So the percentage of carbohydrates in the snack pack is about 60 grams.

You can also use compatible numbers to estimate the rate and the base.

1

4

1

4

Memorizing benchmarkpercents can help you use mental math and estimate.

grams of

carbohydrates total mass